<< I'm pretty sure the on Geforce 4 cards that have the DVD codec is the Ti series.. Nothing on the Nvidia site says the MX's have it... I'm waiting for a 4200 as well.. Should be able to clock it to atleast 4400 specs... >>
DVD is enhanced in the GF4MX line, an added feature.
Overall, would you rather have old tech or new tech. If they are the same price, the best bet is to get the new TI4400 cause it has twice the ram and a faster clock and a broader featureset than the GF3 TI500 so it would be the best bet to get the Ti4400. Hopefully the Ti500 will be sold out soon from the distributers and they will have to introduce the GF4 Ti4200 which will be the new budget class GF card but it will have all the features and speed of the latest and greatest.