I am almost completely certain that the VPC disc will not suffice for the windows upgrade.
You won't need two optical drives if you get an upgrade disc. If you are doing a clean install on a blank hard drive, you will be prompted at some point in the installation process to insert a cd from a previous windows version. For XP I believe it requires 98 or later. You don't need the serial for the original disc, and I think it can even be an upgrade itself. If you know ANYONE who has any sort of gateway, dell, HP, or perhaps even one of the dozens of other ill fated companies from the late 90's, talk to them. The further back toward the 98 era the better, because starting around ME the computer companies started making proprietary recovery discs, and I'm not certain you could use one of those for the part in question for the XP installation. If they did come with a full install disc for any of the windows versions, you're going to be in luck.
If not, my father has a full install disc for XP pro that he'd be willing to part with for about $100. He just got a new PC with XP home, so he doesn't need the old one any more. I'd keep it, but my educator's upgrade copy works just fine when I pop in my old 98 disc. However, if you can find someone that has any old windows disc, I'd get one of the upgrades, because they're only about 80. I've used them for about 5 or 6 machines, and they work just fine.
PS. Drop the extra 6 bucks or so on the real 9800 pro. It's 222 for the ATI retail version of it on newegg, as opposed to 216 for the sapphire.