As I said in #1 and as Jim said in #5 an nVidia card does not, from all the documentation available, support hardware MPE with less than 1Gig of video ram (I think the actual number is 896 available... but since cards are not built that that amount, the 1Gig minimum is usually quoted
If your card is working with the hack, I don't think you really have less than 1gig of video ram