Well for one your roms don't need to be changed in any way if they work on the pc. Now I'll make a list of the best(well at least in my opinion) emulators. N64 - Surreal : It runs certain games well but not all of them. Version 2.0 will hopefully come out soon and it's supposed to be kick ass. SNES - XSNES9X : Can play almost anything without any noticable difference from the real thing. GBA - Xboyadvance : My favorite emulator since it plays the games very well. Some games do tend to slow down a bit, but not much. CPS1/2/Neo Geo - fbaxxx : All in one package emulator sinse it plays all three systems really well and it can play certain other kinds of arcade games. Hope this helps.