reply to Dominokat
Re: OS upgrades That MacBook has EFI32 and won't boot a 64bit kernel. I'm in the same boat with my 2006 Mac Pro...64 bit processors but 32bit firmware. ML will only boot to a 64bit kernel.
It is an artificial limitation as early builds of ML would boot on EFI32 machines and some users have found workarounds for getting the 64bit kernel booted on EFI32 machines.
Now there is better 64-bit support from Microsoft for EFI32 Macs than you get from Apple.