HardDrake is a handy utility that can be used to display information and help configure devices on a PC. It's easily started from the DrakConf control panel.
As seen in this graphic, if a disk is designated as "master" on the Primary IDE bus, Linux names it "hda" which means "hard disk a". If another disk is attached to that same bus as the "slave" drive, it would appear as "hdb".
You'll often see a CD-ROM drive as "master" on the Secondary bus, that would make it "hdc". Linux makes no distinction between an IDE hard drive or CD-ROM when it comes to device names.