S'cool. GPUs are meant to run through highly-parallel tasks, like computing the color of an ass-ton of pixels (1080p is 2,073,600 pixels per frame) and spitting them onto the screen. While GPUs have been used for other tasks, these tasks are ones that can be paralleled as well. Video conversion is one such task, there's a ton of data, and it can all be run through in any random order as long as it's all done at the end. However, emulation is almost the opposite. Even emulators for the PS2 and GC/Wii only use up to three cores at a time, and demand a lot of power from them. That type of thing would run extremely poorly on GPUs, because even though they have a lot more total power... it's because of the sheer number of cores (my HD 5770 has 800 "cores"), but the issue is that the individual cores themselves are very weak. That's why you don't see GPUs used for other tasks, like web browsing or file searching.