you're on the right track, but i'll try to simplify the step-by-step. if you want to run windows on a mac you have two basic options. Boot camp and virtualization.
Boot camp comes with mac os 10.5. You will need to have a copy of windows with an activation key, and you should do some research about which versions of windows work (windows xp pro service pack 2 worked for me). Boot camp offers great performance but you have to reboot in windows and leave your mac os completely behind. Since you've got all the stuff on your current pc, I wouldn't go this route.
Provided you're not running graphics intensive programs virtualization is a great option and you can get a free trial to either vmware fusion or parallels. You are correct that you will need a copy of windows if you go this route as well.
You may, however, be able to image your current pc rather than install a new copy of windows in your virtual machine. the link i sent above for vmware converter claims to be able to clone an existing physical machine. In this case, you'd be able to run vmware converter on your old pc, make an image package of all your old windows stuff, install vmware fusion on your mac, transfer the image file from your pc to your mac, and then load up your old "pc" as a vm on your new mac.
I wish i could give you a better step by step than this, but I haven't done it yet myself. Planning to try it in the next week, and i'll repost with my results.
The biggest potential problem that i think might come up is actually transferring a massive image file from the pc to the mac.