7800GS Balance on Athlon XP 2.7 GHz system?

Hi - some advice needed.

Would a 7800GS outgun my Athlon XP 2.7GHz based system or should I target a lower spec AGP Video Card? This will definitely be my last graphics upgrade in this system as I was considering a wholesale upgrade to Athlon X2 4400 + 7800GT and then I found out about the 7800GS! If it keeps me in the running for the next 12 months or so then job done. Changeover cost is approx £110 after I flog the 6600GT.

Specs:

Athlon XP Barton @ 2.7Ghz
2 x CMX512-3200C2
NF-7 V2
GF6600GT 128MB @ 594 MHz / 1154 MHz
Tagan 480W PSU

3D Mark 05: 4026 http://service.futuremark.com/compare?3dm05=994235

HL2, FEAR & Doom 3 play acceptable @ 1024x768 with satisfactory eye candy ... but I want more!