Just some quick comparisons of benchmarks of my old machine (Athlon 800) and my new one:
| Benchmark | Increase |
|---|---|
| CPU int (dhrystone) | 2.83x |
| CPU float (whetstone) | 3.38x |
| CPU MMX/SSE | 2.59x |
| CPU 3DNow! | 2.49x |
| RAM int bandwidth | 3.95x |
| RAM float bandwidth | 4.05x |
| Cache and RAM "combined index" | 3.77x |
| 3DMark 2001 | ~4.75x |
I certainly don't think I have the most beastly machine in the world (Nomad has more memory and a pair of RAIDed SATA drives, for instance, and at least one person I know at work has a Radeon X800), but I'm amazed with how much faster this machine is than my old one. I guess that's what happens when you wait 5 years between upgrades.
Update 08-28: 3DMark 2003 benchmark for the new machine: 3811 3DMarks.
Update 08-30: Doom3 High Quality timedemo: 30.4 fps (I couldn't run Ultra Quality because I only have a half-gig of memory)