knowing Packard hell like I do, a 250W PSU. probably, do you know if you got a quad core and 3G RAM?, with out a PSU 8600GT or a 9600 GT(or ATI equal), with a PSU, well take your pick, whats the processor and monitor?
gs lower mode of 8800 series card, gt higher performance, but you can run a either the 8800GT or the 9800GT, these are good cards, somewhat dated, but they are good cards and will work well for you, the 9800GT has 112 stream processors, the 9600 has 64 so if you can rustle up another 29 pds( sorry not an England keyboard), http://www.vipergaming.co.uk/graphics-cards/nvida-gefor...
OK, good Fraggin'
BTW seems the Q6600 will base at abot 100W,and the card is 125W full load, so it's a little close, the 9600GT is still 100W, , so there you have the good and the bad, it's a pity they always scrimp on the PSU, what do you have for graphics now? on board, do you know what chipset?