1) PC2700 RAM does not "kill" an A64 system. It barely has any effect on it whatsoever. An A64 does not need extra bandwidth, and tests on these forums have already proven that. Granted, he could get better memory, yes, but I don't understand why some of you are jumping to conclusions that his memory is at fault. Now, that brings me to my next point.
2) 512MB of memory will not affect his 3dmark05 score in the least bit. 3dmark05 scores are 99% GPU derived. The only way you are going to see any visible difference in score derived by your system is if the rest of your system is DRASTICALLY more powerful or weaker than what you are comparing to, and even then it won't be more than 100 points differences. When I say drastic, I mean from something such as a P4 2ghz to an FX-57, and even saying that that will show a 100 point difference is being generous.
However, having an extra 512MB of memory WILL help out his gaming situation. Just not 3dmark.