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Try the latest Ubuntu release. The Live CD means you don't even have to install it, and it works great with my C2D MBP (as far as Linux distros go, anyway ;) )
 
I second the motion on Ubuntu working well on a Mac. I even put an earlier Ubuntu disc in a slot load G3 iMac a while back that had a toasted HDD, and all the Live CD apps worked.
I thought it was cool being able to surf the net without a functioning HDD. Reminded me of the old days. That was 6.10 I think. I'm running 8.04 now on another computer.
 
How is Ubuntu AMD64 nowadays? I used the i386 version in 8.04 since the 64-bit one was still lacking a few packages.
 
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