Has your B got 256MB or 512MB?
Why might a RetroPie image not work on a Raspberry Pi?
GnGeo works pretty well on my B 256 though, so it shouldnt be an issue.
I’ve posted details about the neogeo bios file here for gngeo:
http://smartretro.co.uk/forums/viewtopic.php?f=3&t=44
