Reformatting is an absolute joy if you have two hard drives... simply copy everything you think you'll need to the secondary drive (bookmarks, scripts, web graphics, email folders if you archive stuff, etc.) and go to town on the primary drive.
Seriously, pick up a small secondary drive if for nothing else than for reformatting; these days they cost less than a 50-pack of blank CDRs. Of course, you could also go the full-out pro-level route and have one drive for Windows, programs etc. and a separate one for your memory swap files, and use the smaller swap file drive for reformatting jobs.
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