Looks like it will work.
From Crucial -
Q: What memory goes into my computer?
A: DDR2 memory with support for DDR2 PC2-6400, DDR2 PC2-8500 speeds.
RAM you want --
XLR8™ 4GB (2 x 2GB) DDR2 1066 (PC2-8500) CAS 5 Dual Channel Memory Kit
Edit: Don't go above 2GB sticks though, just noticed on the website that: Each memory slot can hold DDR2 PC2-6400, DDR2 PC2-8500 with a maximum of 2GB per slot.*
*Not to exceed manufacturer supported memory.