The first thing I would check would be that the jumpers on the HDD are set correctly. The main HDD should be at the end of the IDE cable, and the jumpers on that one should be set to "Master". If you have a second HDD, it is always preferrable to have HDDs on their own seperate IDE channels. However, if you need to share an IDE chain the second drive should be in the middle of the cable and the jumpers should be set to slave. My advice is to avoid using the 'Cable Select' jumper setting, as this can lead to strange problems.
The second thing I would check is that the IDE drives in the BIOS are set to "auto", so that the HDD parameters are automatically configured. The only time you should have to manually set up the HDD parameters is in the case of having *very* old hardware. Since your friend is running XP, I'm assuming he at least has relatively modern hardware.