QOTD: Boot Camp, Parallels Or Fusion?

I'm sitting here with my MacBook Pro and a copy of Windows 7, wanting to combine the two into the ultimate blogging machine. But how to do it?

I could go the cheap option of Boot Camp, which only lets me boot one OS at a time, and is free. Or I could spring for a copy of Parallels or VMWare Fusion to do the whole virtual machine thing.

So the question today is which should I choose? Either because you want to know what the process is like, or because you recommend the solution – either one is fine by me.