Have you considered a 9600GT? Beats the 8800GT comfortably and an
MSI unit with 1Gb onboard retails from Scan for £155. Rest of spec is close to the 8800GTX - faster GPU but slower mem bitrate, fewer stream/pipes but I think the extra RAM and lower price more than compensate for that.
Take the £250 from the missus and pocket the change towards a game or 2