If you want to dual-boot, I'm pretty sure you won't need to format. Considering you don't have much to back up, try one these guides on APC Magazine.
Dual-Booting Guides for XP/Vista/Linux
Bookmarked: thanks tons, that'll really save some time, bud...
Prog: definitely start a new thread as soon as you get your box, please, since you're going to be the first 'normal citizen' to be cranking this sh!t (Zyb's alright, sure, but he's got 'connections' within Dell, and seems to have a pre-production box with 2.4 proc instead of the 2.8...also, he's rocking Vista-only and with no reformat, as mentioned earlier). I can hardly wait to see the oc'd numbers in XP...I also wonder if there will be any REAL difference between XP and Vista with this setup (at least, on the games that Vista WORKS at all)?
Edit: Oh, shoot, just noticed the 'stock' config has a 2.4 proc as well...anyhow, it'll still be good to see Vista vs. XP on Bioshock and stuff...also, if you can give numbers from the OC of the graphics boards, you would be our god! The proc OC will likely make little difference in games, anyway, though it may cause numbers in other apps to shoot up (i.e encoding/ripping/extracting/content creation software, etc.), though these pale in importance compared to gaming numbers, of course!
Edit 2: Got it yet? Got it yet? Got it yet? Got it yet? Lol...are you at work or something?