Seven there's loads of cards on this page here (ATI),
http://www.overclockers.co.uk/acatalog/Online_Catalogue_X1300___X1600_Series_708.html
Your psu does concern me however, most of those cards seem (at first approximation) to be devoid of a pci-e power connector. If any of the guys here know any better I'm sure they'll chip in.
The other option is to ring OCUK tech dept, and ask them about a card you can pick out from that list, tell them your psu specs. I'll do a search over at the ATI site to see what the power requirements are for the 1600 card at the bottom of that link.
Come on guys, soemone must know something that'll perform ok with those games. Unfortunatley I have 2 1900's in Crossfire, so my knowledge of the lower cards is very limited.
regards
Raja