I've finally decided to format my hard drive and reinstall windows as I've been getting a few weird problems recently.  I have a 80gb external HD that I'm going to back up most of my files to so I won't really lose anything. 

I'd like to partition my main HD into two partitions.  One for windows, and the other for my files.  ramirez was telling me about this on irc and I'm interested in doing this because it means that if I ever had to format again I could just format my windows partition instead of my whole hard drive.  I'm just wondering how big of a partition I should set aside for windows xp.  My hard drive is only 80gb.

Around 10GB to 15GB is my guess, though I personally go 20GB since I don't mind letting Windows have more space than it'll probably ever need.

Yeah, I was thinking 20gb as well since I have the external HD to put stuff on too, if needed.  I'm just wondering what would be a safe amount for Program Files.  I'll be installing a few programs but not too many, and not really any PC games (at least nothing made in the last three years).

You could always just relocate your program files folder to the other partition if necessary.

I'm guessing that's as easy as moving the folder, I won't need to set permissions or change the registry or anything?  If that's the case then I would think 10gb or so would probably be enough for windows.

I do away with installing programs onto C: altogether.
Usually, the only stuff that gets installed into C: are system utilities and media codecs, things that wouldn't work anyway if I were to reinstall Windows.

You could create a symbolic link, or you could just change the install path to the other partition when it asks where to install.

I dual booted XP on a 10 gig partition once, but I wouldnt go any lower than that. Since after the installing some basic software plus the OS itself I had like 5 gigs left.