What is your timeline? If you have a week or so, I would recommend setting up a Dwolla & Mt Gox account. You will have to setup a bank account in Dwolla and that will take a couple of days to verify that you actually own the account. They will deposit a few cents in your account, then you tell them how much they deposited to prove you have account access. After that, the funds take a full 3 business days on average to get from your bank account to Dwolla then an hour or so to get to Mt Gox from there. You will get the most bang for your buck there since the dwolla fee is only 25 cents and the Mt Gox transaction fee is only 0.65%.
If you absolutely need it ASAP then the fastest way I know to do it is to go through Virwox. You first need to setup an account with VirWox. To do this you will need to have a second life profile and attach your profile to your Virwox account in game. If you don't have a Second Life account, you can get one for free. You need this because technically, you aren't buying bitcoins on VirWox. You are buying linden, then trading them for bitcoins. You can fund your account with PayPal, buy the linden, then trade it for bitcoins. I really don't recommend this unless you are really in a fix or you think the market is going to surge like crazy. This is because I think there is a 2% transaction fee to use PayPal for funding, then at 2.50% transaction fee on your USD/Linden purchase. Then a 1% transaction fee for your BTC/Linden purchase. You will pay somethign like a 5% total fee to move the money, but I recall setting it all up in an hour or so when I tried it out.
I mean no offence, but no one is going to do a strait trade with newbies like us.