Local is a good choice, often you'll find people selling at or slightly above MT GOX price.
localbitcoins.comYour next bet is Coinbase, which requires you to connect your bank account. It takes a couple of days to process this. Finally, the most popular trading platform, MT GOX itself, which I do not recommend if you're trying to buy BTC easily--but once you finally, FINALLY, get into it, it's great if you're getting serious. However, many people are avoiding it right now, due to issues you'll find in other parts of this board.