The one thing to check for is what interface type the computer has available. SATA is current and should be used if possible. PATA (ribbon cable) is older, but still fast enough for CD drives. Apart from that, buy one that looks good ($35 would be the most I would pay for what I use) and make sure that it comes with a cable or that you get one for it. Nothing takes the fun out of a build like finding you're one cable short.