Those games are way to big . And they require the rom be loaded into memory to be played . Considering the gp2x only has 64 megs that is your bottleneck for unzipped roms . It was the same thing for xbox so I got a 128 meg ram upgrade .
it might be able to do virtual memory in the future but SD cards are just way to slow .
Basically I would not hold my breath until they figure out how to upgrade the ram .