OK, you have two possible options here.
The problem is that the bios is too old to recognise the drive size correctly. The two ways of over coming this are :
1) Buy an ATA controller card. This is a PCI card with its own bios. You connect the 80GB drive to the card instead of to the motherboard. As the card has its own bios, it should recognise the drive correctly.
2) Download Datalife guard for DOS from this link :http://support.wdc.c...dex.asp?swid=23
Download the dlgsetup11_dos.exe file & run it. You will need a blank (preferably new) floppy disk. This will create a bootable floppy with data lifeguard on it.
Once its done, switch off the PC & reconnect the 80GB drive. Check that the drive has a single jumper over pins 3-4 only. This will set it as a slave without restricting the size.
Make sure you are using a PS2 or serial mouse, not a USB one.
Insert the floppy disk & switch the computer back on. The system should boot from the floppy. If it doesn't you will need to go back into the bios & change the boot sequence so the floppy appears before the hard drive.
Select the 'Setup your hard drive' button & follow the instructions on screen.
If it asks you what the drive will be used for, select the 'additional storage' option.
Make sure that you select the correct drive (i.e the 80GB drive, not the 10GB!). Also, I suggest you select the Advanced Installation option, when prompted. This will allow you to create more than one partition.
When asked for partition sizes, create two 40GB partitions. (This is because Win98 DOS based programs cannot recognise more than 64GB at a time & may cause problems)
In theory, this will create the two partitions for you & install the overlay software automatically.
BE WARNED - YOU WILL LOSE ALL THE DATA ON THE 80GB DRIVE!!
If you have any questions or if data lifeguard doesn't seem to be behaving in the way I've described, let me know. If in doubt, exit out of data lifeguard without making any changes & let me know what the problem is.
If both your hard drives happen to be Western Digital & you are worried about being able to select the correct one for partitioning, then let me know & I will talk you through how to disconnect the 10GB drive & run data lifeguard with only the 80GB drive installed.