Are you primarily concerned with high-capacity or fast access? If you wish for the latter, look into the Western Digital raptor series (10k RPM), available in 36.7 GB and 74 GB varieties. If you are looking for large amounts of storage, look into the WD and Seagate models. 200GB seems to be the best value per dollar right now, whichever brand you choose to go with.
Unless you are getting a Raptor I would definitely recoment a Seagate. I have had 2 WD and one Maxtor die in the last 5 months and have had no problems with my Seagates plus they are quiet, fast and have 5 year warrantys