Did this just start happening, could you see the drive before?
Did you install any software inbetween or make any other changes to your system?
Doesnt matter if one drive is NTFS and the other is FAT32, although I would make them both the same, you are looking for problems in file transfer with one NTFS and the other FAT32.
Does your bios see both hard drives?
If they are ide check all your connections, make sure it is jumpered correctly and i imagine you are using 80 wire ide then make sure the drive is in the correct spot on the ide cable. You havent said if you just installed this drive or if it was working ok before or what, so its a bit hard to diagnose the problem.
What size are your hard drives?
You didnt give us a lot of info to work with, lol. Not a big deal, but we do need the info.
Have you recently installed any service packs to win xp?
thanks