I have 4x1GB modules of the Dominator XMS2. I have a mate who would take them off my hands for £30 and I'm thinking of buying this stuff.
http://www.overclockers.co.uk/showproduct.php?prodid=MY-173-CS&groupid=701&catid=8&subcat=817
Two reasons, using two modules instead of four puts less strain on the northbridge (had to lower my CPU overclock after I installed 2nd set of RAM) and I could upgrade to 8GB if I wanted.
http://www.overclockers.co.uk/showproduct.php?prodid=MY-173-CS&groupid=701&catid=8&subcat=817
Two reasons, using two modules instead of four puts less strain on the northbridge (had to lower my CPU overclock after I installed 2nd set of RAM) and I could upgrade to 8GB if I wanted.