I play C&C generals, warcraft3, and sim city4.
So on the games he plays all are rts and all are directx 8.1 based. They all rely on the cpu for AI and require lots of ram (which he has). All three are likely to run at less or around 30fps on a top notch system. By going for a faster cpu you will help to reduce slowdowns. No your not going to get massive increase in frame rates but thats not the point. An example is in the rts game I play warrior kings. I have 2 machines 1 I play games on (usually) and my other machine for working on. The first has a 2.4c P4 512mb memory and an ati 9600pro, the second has 2 x 2800mp processors 512mb memory and a fx5200. Whilst the first is undoubtebly faster than the second when the game is in the full heat of battle with 400+ people in an army fighting the second will have higher frame rates and be less choppy, this to me is better than highs and lows.
You can quote UT2003 numbers all you like the simple fact is he did not say he was playing fps games, had he said that I would have replied differently. but in RTS games High FPS means nothing when you are in the middle of battle and they drop to low numbers.
You may not agree Rollo, but if it was me I know which I would choose you may be different. Either way its not bad advice, just a different opinion.