Help - Hard Drive Crashed

If it boots once it's cooled down, it's probably the drive dying (espeically based on the "buzzing noise", although I suppose that could have been caused by another component overheating). I'd take your brief reprieve to get any worthwhile data off the drive while you still can. In fact, if you have an external, you might want to make a clone of the drive if you can keep it running that long, so you can re-clone to the replacement and save yourself some reinstall time.

Your PowerBook should accept more or less any PATA (AKA ATA, AKA IDE) hard drive, and I don't believe there's any capacity limit (if there is, it's 128GB, so basically unless you buy one of the very new 160GB drives, you're fine). It's possible there's a thickness limitation, but not that I remember.

If you want to see how others fared with compatiblity of a specific drive in your specific computer, you can check out the drive database at xlr8yourmac.com--search for your computer and the particular drive you're interested in, and you can probably find out if it worked for others.

Installation is a pain, but OWC (macsales.com) may have an instructional video or document, depending on the model, and if they don't one can be found elsewhere online (xlr8yourmac.com is another place to try).

If you want to get something that you know will wokr, OWC is again a good option--they only sell drives that they've tested are fine in your particular model of PB. If you feel confidend and want to save a bit of money, I'd recommend trying ZipZoomFly.com--they have very low prices and a wide selection. If you go to their hard drive section and click on the "Mobile" subheader at the top, pretty much everything that shows up should work for you.