The Radeon 9500 Pro is the card I'd go for. It supports Directx 9 and in a number of cases AA and Anisotropic filter perform better than the Geforce Ti4600.
Edit:
The Geforce4 Ti4600 is still a great card. In non-AA situations, it is better than both the Radeon 9500 Pro as well as the GeforceFX 5600 Ultra. However, once AA, Aniostropic filtering, (or both!) are enabled the Radeon 9500 Pro jumps ahead of the Geforce4 Ti4600.
Also note that AA will look better on the Radeon 9500 Pro due to Ati using rotated grid anti-aliasing instead of the ordered grid method.