Dennis, one important thing about emulation is that the system the emulator is running on is much and much faster than the one being emulated. That's why you won't see an N64 emulator on PS2, and no PSP emulator on the Iphone.
I've seen a SNES emulator on PS2 btw, and it wasn't that good either, it definitely didn't seem any better than the Dreamcast efforts, despite the faster processor. Then again, most of them are Snes9x ports anyway. If you're interested in a one stop emulation system, most likely an Xbox will fill the needs, or a PSP for handhelds. Of course the Wii is an option as well