to add to the post above ..
sometimes the old-skool non-sata drives are called pata drives.
(serial ata and parallel ata).
and, yes, as long as your mobo has a primary and secondary ide, you can connect up to 4 pata (ide/uata) dirves. have a look, because i've seen a few boards that have only a primary (and then a couple sata conn's).
put the hdd's on primary connector and the opticals on secondary.
//edit - when you add this new hdd if you get one, check the jumpers! the hdd you have now is probably fine, but look at it anyways (i've seen drives with a master/single setting and a master/with slave setting).
primary master is your sys disk. the new one should be jumpered to slave. unless you plan on reinstalling your os and using the new hdd as your sys disk.