The Radeon 9500/9600 Pro cards have a few graphical goodies to offer the TI4200 doesn't. DX9 support, DIVX enhancement as well as a noticable speed boost.
I'd recommend a 9500 Pro or 9600 Pro card if you can afford it.
If not, the GF4 TI4200 is still a very powerful card at a good price.