All the good ones - diversity counts! (each line is 1 rig)
Athlon MP 2000+ x2
PowerPC G4 1 GHZ
UltraSPARC IIi 167mhz (eventually to be 250mhz x 2, when I get around to installing them)
MIPS R4400 250mhz
That's my dualie Maya 3d graphics workstation (Linux), my Powerbook G4 17" (original 1GHZ version) (Mac OS X 10.3), my Sun Ultra Enterprise 3000 (Solaris 9 8/03), and my SGI Indy (IRIX 6.5.22). All of which are functioning machines, all of which are used quite frequently (typing this on the Powerbook as the dualie crunches on some Maya stuff and the Enterprise 3000 provides the network routing).