No need to reinstall everything! I just moved my WinXP Pro from C: to L:, removed C:, then renamed L: to C: Since the new partition was larger than the old one, I now have more space available for my (new) C:
I used http://www.softpedia...ry/DrvClonerXP.shtml
but could have used http://www.softpedia...ry/DrvImagerXP.shtml
Both free, although the author's website has been down for a long time.
Also, to search for all C:\ and replace with L:\ in my registry, I used http://bladesdev.com/regreplace.htm
(click all 3 check boxes on right side when you use it.
The helpfile for DrvCloner gives the exact things you need to do. I did have to make the new partition 'active' in Drive Manager in WinXP, don't think that was mentioned in the helpfile. I did have a scary time, but since I had made my boot.ini file able to handle booting from a Windows partition on any of my hard drives (in case removing a drive affected which drive # Windows would be on), I was able to continue ok. Part of the issue I had to get around was that my original C: drive was IDE, while the new one was SATA. I had to play with my motherboards CMOS/BIOS settings that affect which hard drive is bootable.
Anyway, just wanted to try and save you the time/trouble of a re-install and the mess of having to re-install all your software, then set it up the way you had it before.
Hope this reaches you before you re-install.