Yes, from everything I have heard, they will be basically no performance different between 128bit SDR and 64bit DDR.
Why get the Geforce2 MX over the Radeon SDR? Well, it is cheaper since the suggested retail is $150 for the Radeon, while it was $120 for the MX and when the MX came out, many were way over $120. The MX is faster in 16bit though lags behind a little bit in 32bit past 800x600 (?). I'm not sure exactly so you would have the check out Anand's Radeon SDR review.