First, to day trade stocks, brokerages will require a minimum account size of at least $25,000. Also, it's a risky game — very few people succeed at it. Those that do have generally become highly skilled at longer-term trading (position trading over several weeks, months or years or "swing trading" over days or weeks) before attempting day trading. There is no software you can use to make your decisions — that is totally up to you. It requires a great deal of experience (I would say, many years) to become a successful day trader.

Trade first on a simulator to test your theories at Investopedia.com

When you start making "virtual" money, then you can risk your own.

http://simulator.investopedia.com/home.aspx

http://investopedia.com

http://investing.sitesled.com/

http://futures.tradingcharts.com/learning/

Blogs

http://winners-and-losers.com/

Training & classes

http://bettertrades.com

http://investedcentral.com

ETF news and analysis

http://ETF-World.Org/

Article: Trading is Timing

http://www.investopedia.com/articles/trading/06/TradingisTiming.asp

Stock Charts

Bigcharts.com

http://www.stockTA.com

http://www.stockcharts.com

http://www.incrediblecharts.com…

www.prophet.net
americanbulls.com

Books on Investing

"Which Is Better, Buy-and-Hold or Market Timing?"

"Do You Have What It Takes to Be a Market Timer

The Beginner's Bible in Technical Analysis is:
Edwards & McGee"Tech. Anal. Of Stock Trends"

Droke, ClifTechnical Analysis Simplified

Kahn, Michael N.Tech. Anal. Plain & Simple

Kamich, Bruce M.How Technical Analysis Works

Lefevre, EdwinReminiscences of a Stock Operator

Lofton, ToddGetting Started in Futures

Lowenstein, RogerBuffet (Warren)-The Making of a Capitalist

O'Neil, William J.How to Make Money in Stocks

Oz, TonyHow to Make Money From Wall Street

Rotella, Robert P.Elements of Successful Trading, The

Schwager, JackStock Market Wizards

I'm not sure if I understand your question….
Are you asking if its possible to have a career in day trading?
Sure, you can be a stock broker…
Or
Are you asking, if you can make a living (support yourself), by trading stocks.
In this case, I would say probably not.
Even professionals that have spent their lives studying the stock market have trouble predicting changes. What hope does that give to an average person? Furthermore stocks are meant to perform well in the 'long run' and not from day-to-day.
I suppose its possible to make constant gain if you index the 'entire market', however it probably won't be enough to let you quit your day job.

For the price, you can't beat Telechart. It has everything you'll need in one place. Speed and efficiency is unsurpassed. You can sort thru 8000 stocks in seconds to find any criteria (and I mean ANY criteria) you can think of. If it's not a function of TC, then you can easily write your own personal criteria formula.

Each function key on your keyboard can represent 12 different chart configurations, so you can look at these 12 different criteria in seconds. As soon as you hit the "F" key, the chart is displayed on your screen.

Did I mention that it has all the industry groups? If you looking at a stock and you want to know how the industry is doing, just switch over to the industry group with a click of the mouse.

All the indicies are also grouped together. You can also download that group of stocks that meet your criteria into a CSV file for importing to XL. I especially like this feature.

The support you get from the Wordens is unsurpassed also, and I couldn't get by my day without reading the daily wisdom from Peter or Don.
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Day trading is tricky, whether your doing it for real or as an exercise like you are doing here. The primary problem is that over very short periods of time, individual stocks as well as the stock market indexes can be extremely volatile. You might as well throw darts at a dart board marked out with all of the stock symbols because it pretty much is sheer luck over such a short time frame anyway.

I'm not familiar with CNBC's Million Dollar Portfolio Challenge, so I don't know what their investing time horizon is like for this task. Depending on how long that horizon is, I would probably make different sets of choices for your million dollars. Over a longer horizon, I would probably do some research and then pick 20 stocks, $50,000 each, and then let them sit there and do nothing for several months as that is, historically, the best way to get a return on investment. Too much "in and out" of the market would kill you on commission costs alone anyway.

Goldberg and Lupercio, two analysts of the online trading industry, estimated that about 40% of all trading volume comes from a group of 50,000 "semi-professional" traders who use the major online brokerage firms. The analysis was for the year 2003.

So a good guess would be 40%.

You better know what you're doing and have been doing for a while. and thay you understand the maket and the rules governing it.

Here are four rules you must have, if you don't you will loose money
1 – A written sound trading/investment plan with rules that will not only help you but more importantly protect you, mostly from yourself.
2 – Sufficient trading/investment capital. Use your own money, there’s no need to go into debt so that you trade/invest.
3 – A written money management program in place. Remember never invest 100% of your capital into any one security and never have 100% of your capital invested.
4 – A full and complete understanding of the rules & regulations of the industry.

Here are some of the rules that I follow, in additiona to the four cardinal rules above.
Never buy or sell based on anyone's, including your own, market predictions.
Stick with up-trending stocks.
Never buy stocks in danger of filing for or actually in bankruptcy.
Never average down.
Always sell when management cuts sales or earnings forecasts.
Only buy stocks with real sales and real earnings.
Always diversify between industries.
Don't buy stocks just because they've gone up.
Never sell a stock because an analyst proclaims it is overvalued.
Always look for companies with new ideas, new styles or new products.
Orders after an execution – a “stop loss”
No security is to be purchased at a price that is below the 50-day moving average price.

Good luck, based on your question, you're going to need it

You might want to take a look at http://www.top10traders.com – this is a free site that lets you create a portfolio of stocks with $100,000 in "play" money. Each day the site ranks the best performing portfolios, so you can see how your picks perform compared to other investors. You can read posts on investing from the best traders, as well as share your own investing ideas. There is a charting feature, so you can see how your portfolio performs compared to the S&P 500. Also, you can create your own "group" so that you can see how you are doing compared to your friends.

Here are this month's best traders:

http://www.top10traders.com/Top10Standings.aspx

Hope this helps.

>>How, with only 10 billion shares outstanding, can XXX be so actively traded at this volume and why would XXX sit at the same price and trade billions of shares, when all press and reports about the company are positive?

The market is at a price consensus or is in a consolidation phase. The bulls and bears are in consensus; no one is more powerful than the other.

You will also find that penny stocks are usually less volatile than bigger value stocks.

>>My take is that someone is deliberately swapping shares, huge chunks at a time, at ridiculously low prices to keep the stock price down? Why go to the expense?

No I doubt anyone would be doing that deliberately. There is no point to such exercise – waste of time and money.

Maybe people who bought earlier at a cheaper price are taking profits and people who are hearing the news are buying in.

Good Luck!

Yes as long as you have a margin account…. but the "I don't know much about retail accounts" tells me you don't need to be on the short side of the market. There are other requirements to short and it varies broker to broker.