hard drive unseen

My son has an old p3 machine on which we run win98 to play old games, he had a 20gb hard drive and wanted to upgrade to an 80gb. The drive is not seen by his machine. It will work on my p4 as master and slave, and using my machine I have formatted it to FAT32 and installed win98se.
Help

There can be a number of reasons why the drive is not detected.

1. The drive formatted as one large partition is not compatible with the system.

2. The drive is not jumpered correctly to be compatible with the system.

3. The hard drive is too large for the system's bios to recognize it.

What is the make and model of the system, as well as the hard drive?

You may have to partition the drive using the hard drive manufacturer's utility (on the system that you expect to use it on) for the utility to format it properly, then for the system detect it properly.

The drive is weatern digital 80gb 8mb IDE
the partition is now 74.36 Fat32, though originally I partitioned it as NTFS and made the first partition 40gb then 30gb then 20gb to try to make it work, I then changed to FAT32 thinking this might be the problem
My sons computer has only one hdd which has been set to master, I have changed the hdd before and had no trouble with it, I always set the hdd to master on his. I did remove his DVD drive and put this drive in as slave, but the system wouldn't boot as it could not see it.
My sons system :
Processor Intel Family 6 model 7 501
Bios: Award software 10/20/98
Dos: 7.10

Thankyou

I got in touch with novatech, tech support, they said the problem is the motherboard because it is an old computer, and the only solution would be an IDE controller card which would allow the drive to be put in as slave, or total upgrade.
Thanks for all your help everyone
Dai