MaximumPC did a few gaming builds recently that should be able to kick Cataclysm's rear end.
http://www.maximumpc.com/article/fea..._gaming_pc_647
http://www.maximumpc.com/article/fea...g_pc_step_step
Obviously, the prices for everything is in USD, since it's an American magazine, but the cost difference shouldn't be a whole lot different from what an old friend used to tell me (he's also from Belgium =P).