Looking through this thread, I see discussions of nVidia kernel modules conflicting with 64-bit kernels, enabling BigMem on 32-bit kernels, etc., etc.

http://ubuntuforums....rnel+guide&page=6

Do you need 64-bitness, or do you just want to be able to use all your RAM? The 64-bit kernel should obviously do both, but maybe a tweak to the 32-bit kernel will do what you want.

As to how one does go to 64-bits, my reading is you have to use a 64-bit installer to get the 64-bit kernel - http://ubuntuforums....it+kernel+upgrade

As to how one installs a "bigmem" kernel, well it looks like you'll have to roll your own as Ubuntu doesn't provide one, unless things have changed: http://ubuntuforums....php/t-725567.html

:-(

Good luck. HTH.

Cheers,
Scott.