I am only going to consider the type of reinstalling in which you wipe it all out and start from scratch, since to me that would be what you were asking for, and not the type of 'repair install' that just refreshes system files.My XP desktop:
Still had original factory install it had when I got it in 2006, when the hardware mishaps killed it near beginning of March .
My daughter's XP laptop:
Had to reinstall XP after replacing the hard drive that died. That was about a year ago.My old long dead P3 (WinMe):
Twice, the first day I had it, monthly after that.
This 11 year old pc with Win98SE
(before I wiped it out to install ME): 2 years on a single install, although I probably should have wiped it the day I got it.This 11 year old pc with WinME
: Still going strong and stable on the install from 2002, with only 1 repair install to fix a botched upgrade to IE6, some years back. It's starting to show it's age, though (a bit slower than it should be), so as soon as I have another machine to help with making backups, I am going to wipe it and reinstall ME, keeping the software collection on it kind of lean and get a bit more serious about testing stuff & writing for my long neglected Snailware blog