In my office, I have:
Thinkpad T42p, 14" (1400x1050)
2ghz, 2GB RAM
IBM Intellistation
Dual P-II 400mhz, 320MB RAM
Matrox Millennium II, 8MB
This is my main machine, believe it or not.
Since I do device driver development, I have a number of development machines that I can treat as my own but I generally don't keep them in my office.
IBM xServer 226
Dual 3.2ghz Xeon, 2GB RAM
IBM xServer 235
2.4ghz Xeon, 512MB RAM
I have a couple of these with various operating systems
IBM xServer 360
Dual 1.8ghz Xeon, 4GB RAM
HP j6750
Dual 850mhz PA-8700+, 2GB RAM
HP C3000
Dual 400mhz PA-8500 (maybe 550mhz), 512MB RAM
A couple Power4-based IBM RS6000s whose specs I don't recall
Edit: Oh, and I have a Pentium 133 (not mmx) sitting powered-off in the corner. It's somehow fallen through the cracks of the company's inventory system so it technically doesn't exist