Dude - before you decide to reinstall, I definitely agree that you should backup your /etc and /home directories. If I understand your situation correctly, you want to preserve your important personal data (which should be located in /home/...) and whatever important configuration files you have (which should be located in /etc) but otherwise you want to do a fresh install. If so, as long as you can save those 2 directories somewhere (another disk, burn them to a CD, copy them to a USB thumb memory stick, etc) you should be golden. As for me, the critical things I'd like to keep are my XF86Config file, fstab file, and my Email, photos, and other documents. That's just me though, and no doubt other people would recommend saving other files too. For me though, if my personal data is OK, my machine boots, and my monitor, mouse, and keyboard work OK, I figure I can rebuild anything else I might need.
As a side comment though - are you really sure that the install is totally fried? I'll guess that your system is probably working pretty well, and that you'd just prefer to start over because you ran into some snags during the initial install (which definitely was my situation, I think I installed Linux about 7 or 8 times before I thought it was just right.) If so, it may be worth really analyzing what is working and what isn't. As they say, if it ain't broke, don't fix it. Dunno if this helps, but it's my 2 cents -- J.W.