Here's another vote for a dual Athlon MP machine - I currently have two, one based on the MSI K7D Master-L and one on the original Tyan Tiger MP.
The Tyan with Athlon 1700 MP's and the MSI with Athlon 1900 MP's.
Each has:
1 GB of DDR SDRAM
two Seagate Barracuda IV 80 GB drives
a Plextor CDRW and a DVD drive (no DVD burner yet)
Gainward Geforce 2 Pro graphics
Viewsonic MB110 21 inch monitor
Logitech Freedom Pro (cordless Mousman Wheel and cordless split keyboard)
Same keyboard attached to both via a Miniview III 4 port KVMP switch (the P is for USB peripherals)
And for you storage freaks I also have an Adaptec 2940U Pro attached to an external IDE RAID box with just over 500 GB in RAID 3 configuration. At work I just got one with 8 drive bays populated with 250 GB drives, 7 of them running in RAID 5 and one hot spare (see at http://www.acnc.com/02_01_jetstor_iii_ide.html), stark23x - very similar thing coming up using the serial ATA drives.
Only thing I would add at this point is a Samsung Syncmaster 241MP 24 Inch TFT LCD Monitor - of course it costs more than both my machines combined - but what a bueaty. Check a review at http://www.tweaknews.net/reviews/samsung241mp/
