Just get a top of the line system.
Really, it's all pretty straight forward. The faster the PIII processor the better. The more memory the better. The faster the hard drive the better. The better the soundcard the...better. Getting to be redundant.
PIII - 500Mhz or better. Consider Athlon.
Mobo with a BX chipset (no i820)
128MB SDRAM (don't swallow RDRAM just yet)
1 - 4GB 7200 RPM hard drive
1 - 20GB+ 7200RPM 2MB ATA/66 hard drive
4x4x32 CDRW or better yet DVDRAM
4MB standard video card (any will do)
Get a good case and a good power supply...250W or better
17" monitor
Blah blah...just get a fast system. Don't worry about ATA/66 and UDMA/33...they're pretty much the same animal right now with ATA/66 not being much if any faster. The 7200RPM drive is what will give you the big speed. 2 hard drives is the best setup. One drive for your OS's and probably your audio software...then the second big drive for your data (music).
Since you're buying
a complete system, you needn't worry about the motherboard too much. Just make sure there is no integrated sound, video, or networking.
RDRAM is still VERY expensive and cannot be utilized properly by the i820 chipset...and therefore should be avoided. It will be cheap one day...so wait for that day. Get a minimum of 128MB SDRAM for now.
If the machine is just for recording, get any old PCI or AGP video card. Nothing fancy.
You will love yourself if you go with at least a 17" monitor. They can be had for just over 200 bucks from Hitachi, Princeton, Viewsonic, Mag, etc...
You want a case with removable side panels for easy installation of your fancy soundcard and whatnot. Make sure the powersupply is a 250 or 300W or you're asking for trouble (e.g., replacing it). I learned my lesson the hard way. ("Hey, that's pretty cheap!")
Finally, you need external storage so get some sort of CD burner. I have found removable hard drives to be more of a pain than they're worth. Highly unreliable. CDR's aren't exactly *safe* but they'll work much better IMHO....plus you can burn CD's of your own music.
You're gonna spend $1000 bucks or more for this system....but not much more. You'll save a lot of money by NOT buying "multimedia" machines. Yes, you are doing "multimedia", but you don't need the fancy video card and you're supplying your own soundcard and monitoring system.
As far as where to buy....
I had a big falling out with this company because the guys in sales are MORONS. BUT, I have yet to find another line of PC's that are as well built, as cheap, and with a long warranty. I use this company to purchase machines for my company. I was actually ready to drop them last week...but I CAN'T find a replacement! They didn't screw me over or anything...they're just incompetent..."ummm...duh...I dunno...lemme send you to so and so...."
www.globalcomputer.com - check out their SYSTEMAX machines. I'm on a systemax right now (at work)...the server is a systemax, and we have two others in the company. I have never had to maintain them. The prices are good too...just look for a barebones or workstation level machine and upgrade as necessary. They usually come with Asus motherboards, nice cases, and the rest is configurable (usually).
Do not buy systems from the following manufacturers: eMachines, AST, Compaq, HP, PB, and UMAX. None of them are as suitable for recording as machine built from the proper components....even if the specs seem to match.
Slackmaster 2000