Due to the nature of my job, I have some "unusual" computing requirements, and sometimes I'm more in scrounging mode to find what will work. I have a friend I met through here who works for a recycling company in Nashville, and I've bought items from his company before. I've also supplied a few PowerMac G4s from my personal stash for one particular application.
Just to give some idea, for one application I have a 486 running Windows 3.1.1. I have a nice dual Pentium III with ISA slots that I'm going to eventually fit to it, but a newer version of the software is more than I can get the money for now. Going to something newer than a PIII realistically isn't possible, as $3K+ for a PCI interface card is more than I can swing. Also, I've been told that the newest version of the software I can use is iffy on anything newer than Win XP. Still, the device this is operating is $100K+ to replace, and I'm keeping it going as long as I can.
As for my office computer-if I asked for one I'd get a generic Dell box and whatever monitor they're shipping these days. I supply my own Mac Pro and a pair of 23" Cinemas. The only thing I've asked for(and received) was a Unicomp keyboard.