Ebuyer has its higher end value pc back in stock (though usually sells out pretty fast once it is)
http://www.ebuyer.com/product/159381
400£, quadcore phenom processor, 4gb ram, nVIDIA® GeForce GTS 250 512MB DDR3 Graphics Card, 640GB hdd etc
:) good value for money, i got my parents one a while back which works a charm (only issue is build quality can be a little dodge in some areas (the panel next to the card reader wasn't in right (just plastic bit to fill hole, nothing important)
Perfomance is solid though.