The best thing I can say is do NOT get a Maxtor. Thats just a huge no-no. Also, some people have great results from LaCie, others get crashes, they are very hit or miss. The best performance I have ever seen are the 4 year old Glyph drives we use every day here. They are 160GB a peice, and have never given us any problems. They are 7,200RPM. You should also check out Western Digital's Raptor series, the 74GB 10,000RPM drives fucking rock. You can put them in an external case with a FireWire 400/800 port and have no worries. The GB size is really dependent on what kind of work you do.
Are you just recording your own stuff? Or do you have bands come out to do demos? If it's for your own stuff, with the occasional friend(s) doing stuff, I would personally shoot for the 74GB Raptor from WD. 10GB of hard drive space gives you hours of recording time/space at 24/48...so really if you think about it you don't "need" a huge drive. We have several 160GB drives because we do a shitload of work. Sessions at 24/48, and sometimes 96kHz, with everything on the drumset mic'ed, 4 tracks of rhtyhm guitars, 2 tracks leads, 2 tracks of bass (1 di and 1 software modeled), 2+ tracks of vocals...all with plugs, busses...all kinds of shit. Plus our policy is to keep each project after it's finished for two weeks minimum, unless more time is requested...so we're talking a 10GB (easily) session, being held for two weeks, and in two weeks, we can have two more sessions added to a drive. A lot of people opt to pay us the extra $50 to hold their session for 4 total weeks just in case they need anything done to it. So...we have basically two whole drives just full of sessions being held, and then one drive is a dedicated tracking drive. Meaning every session gets tracked to that drive, and when it's finished, we back it up on DVD, then move the entire folder to one of the other drives for storage.
Sorry to be so long-winded about it, but it's really all about what you are doing. Home project or what? Albums or demos? You'd be surprised at how little hard drive space you would need to hold several sessions.
My recommendations are WD Raptor, Glyph GT and 050 series. Other people have had great luck with other drives, but I'm just speaking from personal experience.
~e.a