I am reinstalling XP on my 150GB Raptor and will eventually dual boot with Vista 64 Ultimate as well, but not anytime soon. My question is, how big should I make each partition? I've heard that Vista takes up more space than XP, but I use XP a whole lot more (I don't even have Vista yet, but I don't want to reinstall XP again when I do get it). So is it best just to leave half for each OS, or give one more room than the other, say 80GB and 50GB (after formatting)

Also, after I install XP, is there any benefit/reason not to go ahead and format the second partition that will be used for Vista? I know it will be reformatted when I actually install Vista, but is it bad for the HD or anything to have all of that unformatted space?

Thanks a lot

The extra unformatted space will do no damage. And there will be a side effect, your windows(xp) will be in the fastest part of the drive(the first half). Vista seems to work fairly well even with a slower hard drive(due to super fetch preloading stuff you use often), so when you install vista you should be able to then format that part. I have not done this yet, but i will be doing it soon. For now i have vista and XP on separate drives(2 x 250 in raid for XP and 1 500 for vista).