For future reference check either the Hardware section of this forum, or you can also check out the www.tldp.org
for more info. It's touch and go depending on what hardware. Some has major support such as scsi drives and raid setups, others is completely non-existent, my scanner for example
Anyway, for HD's...
First, figure out where you plugged it in. Assuming it's Secondary Master, hdc should be correct.
fdisk -l /dev/hdc or fdisk /dev/hdc should pull up SOMETHING...
FYI, cfdisk can sometimes be a bit easier to work with.
Check your BIOS, make sure it's getting recognized there first, then if it is, move onto your dmesg:
If it's in both places, then move onto the fdisk/cfdisk program and start slicing. Add a filesystem:
mke2fs -j /dev/hdc<partition number>
Or whichever filesystem you choose (that's for ext3).