(no subject)

So, if I wanted to format my computer because it's being an absolute bitch and freezing for no good damn reason, is there anything I should know about formatting aside from save all your files onto something that's not your hard drive, make sure you can reinstall any programmes you want to have after formatting and... well that's all I can think of. Am I missing something?
And my windows xp disk will work fine to reinstall windows, won't it? Do I even need to do it? Will the hard drive know it's a windows xp hard drive?
Thanks peoples :)