AGP card advice please

I have a AGP setup but the current card a GeForce 6600GT (have been very
happy with it), but it's struggling to run new games at a decent frame rate
at 1280 x 1024, the native setting of my monitor. Will be upgrading the
full pc in a years time, and this one will being going in to my daughters
room.

So looking at one last upgrade for my current AGP PC;

PM800- M2 Mother Board
P4 3ghz
1gb RAM
800gb hard disk space

If I bought the Gainward BLISS GeForce 7800 GS+ SILENT 512MB GDDR3
TV-Out/Dual DVI (AGP), would my current CPU get bottlenecked? would it be
able to handle newer games, ie oblivion call of duty 2 etc? does anyone have
a similar system or comments that would help?

Thanks

John