64bit UT2003 Performance
In pure CPU performance, Athlon64 is about 15% faster than previous Athlon's of identical clock rate for 32-bit apps, and 30% for 64-bit apps, [...] we haven't benchmarked yet but expect it to be faster though less than 30% because the GPU is as significant a factor as CPU
Recent investor articles are putting the release of the 64bit AMD cpu early 2nd quarter of next year.