If you plan on reinstalling the Windows OS, your computer will realize that there is already a copy of Windows 7 on the system and act accordingly. It moves all files from your C: into a Windows.old drive and I believe that is where you can grab up your documents, pictures, music, etc.
I helped out a friend who suffered a horrible computer virus last year and the only option I could have thought of at the time was a clean install. Thought she was going to lose everything. Turns out all the files were moved to that windows.old file and thankfully all her class notes, music, photos, etc were saved.
