Which revision of that ram? That should be on the sticks, following the "C2" part. On their forum, their is a section where Ram Guy identifies which chips are used by which revision. The chip information is helpful because ICs have traits, such as ability to run at tight timings or to scale with voltage. Knowing which ICs are used helps in tweaking the ram, otherwise you have to try everthing, as opposed to eliminating things that you know do not work with those specific ICs. And in the end, some ram simply won't run 2-2-2-7, unless maybe you downclock from PC3200 to PC2700 or PC2100 speeds.
Before you proceed with tweaking the memory...if you don't alread have a copy of Memtest86, download one to use in testing the changes to the memory timings. You should be able to pass memtest after each of these changes before you ever go into Windows or you run the risk of H/D data corruption. There are several other threads on Memtest use if you need info on it.
In the DRAM Configuration screen, below the Max Memclock option is where you change the rest of the memory timings. I presume when you say "bump that up a bit" you mean lower the timings? You will simply have to test your sticks, by changing the timings one at a time and testing as you increase the cpu speed. That first link I gave you included a link (which I've copied below) to a guide on overclocking the A64. You have to play with both, the memory timings and the cpu overclock to get the best overall performance. Simply dropping timings from 3-3-3-8 to 2-2-2-7 will help your performance, but the increase will only be in the 2%-3% range, if that much. However, overclocking the entire system, including the memory speed, while running tighter timings will show big performance gains.
Here is that link again, plus another one from eva2000 at i4memory, both are good A64 overclocking guides. The one from eva is more detailed.
http://www.insanetek.com/index.php?page=overclocka64
http://i4memory.com/showthread.php?t=327