Don't use a discount online broker to buy single stocks, you will most likely lose money.
Having any fewer than 20 stocks in a portfolio will pound your beta into oblivion. And unless you have been investing for 10+ years and really know what is going on you will lose a lot of money and really fast.
Your best bet is to buy a managed account at a large wire house like Merrill Lynch, Smith Barney, AG Edwards, etc. Trust me, I've had many clients try both and it is the same story every single time. Also, you can only get IPO's direct from the underwriter, so if you are planning on investing in Visa or whatever comes next you will not even come close to getting the issue price. That means you must have an account at J.P. Morgan, Goldman Sachs, or Bank of America for the VISA deal.
Also, never take investment advice from this board. ASK A PROFESSIONAL