We didn't have VMware yet, so I had to amass all these junk boxes to build a semi-reasonable "WAN" model to test with. In 2005 we purchased a few licenses of VMware GSX Server and shrunk this test lab down to two boxes, still one monitor and keyboard. I ran out of electrical outlets and came close to maxing out the limits for my office (according to our facilities guy at the time). The heat generation was pretty significant, as were the cummulative buzzing of the cooling fans.
Looking back, I would say that my views of WS03 over WS2K are the same as I have now for WS08 over WS03. The improvements are just as significant, maybe moreso. I sure learned a ton about what to do, and what not to do. There are a lot of things I would have done different if I were doing that migration now. It was a good time though. Good times.