I have original Windows discs sitting right here but for the purpose format/reinstall is there legal *up to date* Windows image available somewhere or is there some mystery method I am clueless about? (there have been 100s of MB updates since SP3 alone)
home/professional OEM/Retail ... What would you be looking for?
Addendum: if you do decide to do a clean reinstall, don't forget to backup all your current hardware drivers first. Hunting down drivers - especially XP drivers - is a real PITA. So if you already have a working machine, take advantage of that and get copies of the drivers prior to flat-lining your current system disk.
In a pinch I'll boot to WinPE, strip the attributes and permissions and toss the old install in a folder, and then just drop the new OS next to the old one (variation on a parallel install). Then I can pick out the driver bits from the old install and feed them to device manager (it's actually a lot faster than it sounds).