don't really understand the point to put Ubuntu on a Mac (i tried),  OSX is quite a wonderful UniX (as certified Sun, i love this point) that fits perfectly with the hardware.

Futermore you are losing the lot of the power management features like put it sleeping nicely.

Linux softwares do not match at all Mac softwares, i couldnt live without NetNewWire, Toast, Transmit, Adobe, Iwork, Itunes, Iphoto and so forth.

i can take the bet safely that you will learn to fully appreciate OSX after your Linux "experience" LOL