So finally Garmin have released so software for OS X www.garmin.com/macosx/.
But it mostly requires you to have bought one fo the more expesive models with USB and not the more popular Serial models. I think I still have a problem of connecting my Serial Garmin eTrex Legend to a macbook via usb. Dont think the serial to usb cable I have is compatible but cant check until I get some software that can try accessing the GPS!
Memory map is Windows only, so it is looking likely that I will have to install parallels just to get the GPS working.
PS I got my GPS from www.globalpositioningsystems.co.uk but it looks like they have stopped trading now :(