Maybe the second hard disk is connected to a seperate IDE controller/SATA controller? Installing/updating the drivers may fix the problem.
Check device management if there are any question marks/exclamation marks. If your disk is connected to a seperate IDE controller (eg. PCI card), and there arent's any driver problems, you may still want to try other drivers.
If you are having the same problem on your friends computer, you probably used the same XP disc, and it may be messed up.
You should really be 100% that it has SP1 or SP2, and has 48bit LBA mode enabled, because otherwise disks larger than 137GB (127GiB) will not be detected properly.
If you don't have SP1 or SP2 you can ofcourse enable it using X-Setup, or by Googling on how to do it manually in the register.
You could also try disabling 48bit LBA mode, rebooting, enabling it again. Who knows, maybe it helps.
EDIT: If both disks are on the same cable, try setting both to Cable Select (CS) using the little jumpers on the back of the disks. Also do this if the slave is connected with a CD-ROM device.
TheMajorMMX - Intel P200 MMX @ 225Mhz - V-Tech (PcPartner) Baby-AT mb w/ Intel Triton TX chipset - Nvidia Riva TNT2 M64 w/ 16MB - 256MB M-Tec SDRAM - Still running.....