Hard Drive Question

I am running windows xp on a p-4 2.4gig with 512k ram. I have two hard drives. One is a seagate 120 gig and the other is a Western Digital 20gig. The 20 gig worked when i first installed it as the slave on my computer. Now the drive is showing up in the device manager but not in the “My Computer” window. I tried removing the 120gig master and setting the drive as the primary master but it isn’t transfering information. What do I do to transfer all the information off the drive since it might be faulty.