You said price didn't matter.
If you don't want to run your system outside standard specs search for some 1GB sticks DDR400 with 2-2-2-5 timings.
(Or 2-2-2-8, the last number doesn't seem to have much performance impact)
You should be able to find some 2GB kits for under 400$.
Just remember to check your mobo manual first to see if the voltage won't be a problem.