Actually, considering the 7000 is a severely disabled Radeon architecture, you will probably find the TNT-2 to offer better performance for older games, as it offers a much improved pixel fillrate over the Radeon 7000.
However, given the bandwidth is about the same for either card, the Radeon 7000 will perform better in newer multi-texturing games, as it offers nearly 2x the texel fillrate of the TNT-2.
Personally, I would opt for the TNT-2, overclocked of course.