what i do for that is that i move the My documents folder to another partition, so if i need to format or windows goes cabum!!! i just loose the little or much information saved on my desktop.
to do this just open Windows Explorer in the accesories or by pressing the windows key + E.
then rigth click on the mydocument folder and click on propierties.
on the target tab you can change the target or move the folder rigth away, this as i said will save many space for the windows partition, and will be even safer when in the need to resintall you dont need to worry about making back ups or save your saved games
the way i have it in most of my computers is a 25gb partition just for windows, then depending on the size or HDD quantity, i have another hDD for my documents and save ISO files, and one more HDD or patition for installing games