Hello,
It depends on what you want to do and what you feel comfortable with. Bootcamp and a VM is nice because if you need to run Windows natively, a Mac does an excellent job of it with Bootcamp. If you want to run Mac OS X and Windows at the same time, a VM is perfect.
If you upgraded to Mac OS X Lion, you need Windows 7, as Apple® does not support XP/Vista for Bootcamp. If you use an Intel based Mac and Bootcamp, you will need IIRC, XP SP2 or Vista using Snow Leopard.
I prefer VM as it does not kill the battery as fast on my MBP as running Bootcamp does. The VM is an easier install, and the VM software will guide you thru the installation. VM's dont require a reformat of a portion of your HD, while Bootcamp does. It may be a little challenging for a novice, no matter how well Apple® writes the procedure.
HTHs
73
Dave L.