You cannot plug DDR3 into a DDR2 motherboard! If you dont think a 400W will be enough - try the OCZ ModXStream Pro 500W - £58 usually. 4GB of 1066 memory should set you back less than £45 as well.
But it says on the technical spec that it accepts ddr3 1600 ram :S Jambo, i think i might just do that, i've had a play around with one of the beta versions a few months back and it seemed pretty stable. edit: actually it says ddr3-1600 under the memory speed, not memory type. why would it say ddr3-1600 in the memory speed but says it only accepts ddr2 ram?