I'm a bit of a computer novice (which is probably why I'm having a problem) so I'll try to be as desciptive as possible

I got a replacement drive - Seagate Barracuda 80GB HD - for Christmas and installed it the same day using the software that came with it - DiscWizard.

I then installed my OS (Windows98 SE), Office, set up internet etc. and everything appeared to be working fine, until...
...I tried to slave in my old Maxtor HD for additional storage.

The computer recognizes the hardware - my problem is that the machine is telling me the drive is empty, but there should be a significant amount of data on it. Almost like it has been reformatted, but it hasn't - that was going to be my next task after transferring my data onto the Seagate.

Does anyone have any suggestions as to how I can get my files back?

Any help is greatly appreciated - thanks

Check the jumper-settings on the Seagate. Master is a jumper on pins 7-8.
See the sticker on top of the HD.
Set the Maxtor to Slave, probably also has a sticker.
The Seagate should be at the end of the IDE-cable, the Maxtor in the middle.
Check that the red-line on the IDE-cable is at pin-1 on both HDs and mobo.

Afterthought: the old maxtor may not like a 80-pin cable. Use a 40-pin for the time being.
80-pin are for ATA-100 and up.