What kinda computer ya looking at? There may be a bit of work to look at. See if you cant take a couple pictures of the inside of your case

1. Make sure it is NOT under warrenty of any sort - if it is, contact the manufacturer and they will tell you a [insert company name] certified tech that would have to do it for you in order to keep your warrenty.

2. IDE or SATA: I am gonna gather you are using IDE cables (thick grey ribbons) but this will dictate which type of HDD to get. If you have a thin red cable going to your HDD, that would be SATA.

3. Drive bays. Make sure you have an area to physically screw this HDD into place.

4: Speed: 7200 rpms will do.

5: Brand: Segate is good. Best Buy deal mainly with Western Digital, which I have no qualms with - but it seems many people do! Don't buy Quantum! Stick with a decent brand.

That is all I can really think of.

g'luck!

Bipper