The conventional wisdom is that keeping the memory and CPU buses clocked the same will result in lower latency that gives higher system performance, and the benchmarks I've seen tend to support that. If you have Unreal Tournament 2003 Demo, why not do some Botmatch benchmarks at a low resolution, to make the CPU and memory more of a bottleneck, and see what the results are?
Actually I might do the same since I've got a 2500+ and a stick of DDR400 myself, along with an A7N8X Deluxe. Where's that UT2003 Demo installer...

Of course, my Radeon 7500 is going to be a lovely bottleneck no matter what resolution I use
