If the partitions are shot to a point that it errors even when working from the cd, that is strange. and unfortunately you may not be able to recover from that. Once you have tried FastGames suggestions, and if it still does not work, I am including 2 links to instructions on how to run debug scripts to wipe out the partition information. The instructions are specifically for Win98 on a FAT partition but I would think that it would work on XP as well. I'm just not sure that the scripts will wipe the NTFS partitions or not as I have not had to o this far to get one working...yet

The first link is to a decription page from FDisk.com and gives a decription of what to do and how to run it etc. The 2nd link is straight to the script to be run. IF you have to go this far just follow the directions exactly and all should be fine.
First page

Script Only

*Debug Scripts compliments of www.fdisk.com*