If you want to compare the Radeon 32mb DDR to an Nvidia card it should be the GTS, not the MX.
The MX comes in both SDR and DDR versions, but the DDR cards use a narrow 64bit bus. The DDR MX cards in fact have LESS bandwidth and are slower because they use 143mhz DDR RAM.
A few of the 32mb GTS cards are down to the about the same price as the Radeon 32mb DDR. MX cards are a good $50 cheaper than either.
BP6, P3-700@770 (for now), 320mb, Creative TNT2U@175/220
BP6, P3-700@770 (for now), 320mb, eVGA MX Plus (dual CRT), waiting for VIVO module