Visual Boy Advance has long since become Open Source. This spawned several variants so we will try to list as many as we can here.
Visual Boy Advance can just like a real Gameboy Advance also play original Gameboy (Color) games.
So there is no need to get a separate emulator. Because of this the author has stopped development of his "normal" Gameboy emulator Visual Boy.
As with most emulators for Windows you may need to install the latest version of Microsoft DirectX.