One nice little addition to UT2003 demo is that it has a built-in benchmark utility.  You can find the benchmark in the system subdirectory for the game after it installs.  The file is appropriately named 'benchmark.exe'.  Run this file, select the resolution you want to benchmark, and it will go through 4 different demos, 2 are "flyby" and 2 are "botmatch" demos.  The flyby demos give you an idea of how high frame rates would be without bots, while the botmatch demos give you an idea of what kind of fps you can expect while actually playing the game. The benchmark actually leverages more cpu and graphics intensive technologies that the engine is capable of. First results, FlyBy:

Unreal Tournament 2003	640x480	800x600	1024x768	1280x1024	1600x1200
Pentium 4 2.4 GHz	177	176	175	146	101
Athlon XP 3000+	199	197	190	156	107
Pentium 4 3.06 GHz	216	213	197	150	102
Pentium 4 3.06 GHz + HT	215	212	196	150	101
Athlon XP 3200+	229	227	210	153	108

Again we can see that the 3200+ is worthy it's reputation athough I do believe that Unreal 2003 is a tad better optimized for Athlon processors judging from the 16x12 resolution. Still, it's a good optimization lead and not a cheat.