I've been an active trader/investor for many years now, survived the dotcom bust, etc. etc. and have a wealth of experience on the subject, so if you have any questions, feel free to ask.
Are you looking at diversifying your portfolio past stocks at all? I deal with a lot of limited partnerships, options trading (both covered and uncovered calls and puts), convertible debentures, income trusts, etc., so again, if you need any advice, just ask. Oh, and most mutual funds are crap. I can outperform them pretty much all the time on my own and without having to incur those stupid MER fees.
One thing I would say though with looking at trading with such small amounts of money as you're looking at (i.e. $100 on a stock) is to keep in mind what your commission costs are in and out and how much the stock would have to go up for you to actually make money. It's all a game of percentages. For instance, if a stock is trading at $5 and you buy $100 of shares, you have 20 shares. Therefore, even if the stock goes up by 50% (which isn't likely), you've made $2.50/share, or $50. Not much at all. And that would be an extreme example. And you can do the simple math in terms of percentages which the brokerage would take of your profit as well, as you'd soon find the are doing much better than you on the trade!

But I understand that if you don't have a lot of money to play with there isn't much you can do...
I would suggest doing a lot of reading and research before investing. If you don't know what NAV, P/E, EPS, etc. even mean, and how to analyze a company's balance sheet and earnings report,
you shouldn't be investing.
It does concern me that you think Sirius is a "blue chip" - they are the furthest thing from it. Their capital burn rate is extremely high and I would be very careful when thinking about investing in such a company - they remind me of a good old dotcom company back in 2000. I got burned on a couple of those, but luckily I short sold many of those stocks as well and made a killing as a result.
As well as fundamental research you should do technical research as well. Learn about stochastics, momentum, RSI, MACD, etc. and that will assist you as well.
Lots to know - do not fool yourself into thinking it's easy to make money on the stock market. I've made mine through a lot of hard work, research, and having ice water in my veins at times.
As I said, if you need any advice, just ask. I have often thought of starting an investing thread here where I can impart all of my knowledge, but I don't know if having that on MacRumors is exactly the most appropriate place for it.
