X2 amd's with ddr2? does it work?

as name states?i think i might be going for the x2 route but i'm still considering my options... so i'm thinking why spend loads on new ddr if i could run ddr2 inside it and atleast it would be a wasted cash investment as i could use it in another system in the future if i choose instead of having obsolete ddr...
so what ddr2 can i use in my Asus A8N Sli Premium when i purchase it next friday? what will be nice to overclock and run games and lots of dual core whore tasks? how much and from where in the uk please?
cheers.

DDR2 memory with AMD CPUs only works with the AM2 socket. Socket 939 is DDR

From most benchmarks DDR2 has no real advantages in real life over DDR1 unless you can aford the exotic stuff and then is it really worth it??