The repair shop was wrong. C is the boot drive. The D drive is the image file for Vista, which is now useless since you installed XP. The only way to reclaim that small D drive is to repartition the whole drive. 15 GB's is not worth the trouble, IMO. You can just ignore it. There is a better solution--buy a copy of Win 7 when it comes out and do a clean install. You will be able to repartition the the drive into one, reformat and install Windows 7. It's an excellent OS.