Here's my suggestion:
1) buy a new hard drive
2) take out old drive, put in new drive and do a fresh install onto new drive
3) update system and all drivers, install standard programs, AH, etc.
4) hook your old drive up as a secondary drive
5) pull whatever data you need off of that drive and onto the new drive
6) format the old drive and use it as a storage drive.
6) first thing to go on storage drive is an image you make of your nice, new, updated, working system, using a drive imaging utility such as ghost or acronis true-image.
down the road, restoring that image is MUCH more convenient than reinstalling.