I have accounts with both Sharebuilder and Scottrade. I like them both. The biggest pro for Sharebuilder is that they offer a basic plan that only charges $4.00 per trade for automatic investments scheduled on Tuesdays.  the biggest negative I found is that Market orders are $15.95. They have a list of over 6,000 stocks to select from - but I've stumbled across a few investments that I wanted to make that weren't on their list, which is why I opened the Scottrade account. Both websites were easy to use and the accounts were easy to setup. Both make it simple to transfer funds between my bank account and stock account. I also like Scottrade's $7.00 fee for Internet transacations. Scottrade also has an actual office in my town - you might check into that.

I suggest Sharebuilder if you plan to invest automatically weekly or monthly to slowly increase your stock portfolio and Scottrade if you plan to invest larger sums.