Installing Win 7 is even easier than XP! No raid drivers to deal with.
Put the disc in, and choose 32bit or 64bit (if your PC has more than 4 gigs ram, go with 64bit)..
its just better.. SOME games don't like it, but you can usually get around that with tweaking it.
As ElfBane said, put it in, and follow the prompts.. If there is nothing on the HD you want, let Win7 format it for you too...