Emulator help!

which emulator can play RETRO roms?

It depends on the RETRO ROMs you want to play. If it's NES, try Nestopia. For SNES, try SNES9x. For Gameboy, try Visual Boy Advance.Anyway, those are just some, try going to http://www.emulator-zone.com/ to check others, they have many emulators available.

For Gameboy, probably no$gb, since VBA can emulate Gameboy, but it's more suited for GBA.