I guess you should consider your budget. If you want cheap, you should be able to get a Quantum or Maxtor 5400 rpm drive for around 85 USD delivered. IF you get lucky, you may be able to pick up a 10 gig 7200 rpm drive for about the same price. If money is not as big a concern, then an IBM or Maxtor 7200 rpm drive is probably your best bet, IMO. Around $100 to $125 for 15 to 20 gig. I assume your BIOS supports larger hard drives, so I would recommend a bigger drive, if your budget allows. They are a better value, meaning more gigs/$. They are usually faster, too.
Chuck