I would also look at the ATI HD2600XT as it can be found a bit cheaper than most AGP 7600GTs.
I would agree with this.
Also i would agree to some extent with what OOOwatah said, yes it is to some extent a waste if you care that some fps are going begging because the cpu cant keep up but it will look good.
I would worry that it may be just too big of a bottleneck though.
Any chance of upgrading the cpu if you try the card and are unhappy with the result?