Well according to this PDF by Corsair:
http://www.corsairmicro.com/corsair/.../Asus-1203.pdf
This is the RAM to go for:
Corsair 1GB DDR XMS3200C2 Pro TwinX (2x512MB) CAS2 (MY-026-CS)
How nice they are to produce a compat chart
Tho, charging £205 is not nice! :pp