I spent a day or so scouring the internet for information on how to boot an OS off of a USB thumb drive on a Macbook Pro, specifically my Santa Rosa MBP (3,1). What I'd like is a portable OS (Windows, Linux, whatever) that will boot both on a PC and on a Mac so that I can take it with me and use it with pretty much any computer. I tried rEFIt, which would get me all the way to choosing to boot off of the Ubuntu OS I installed on the USB stick, but then it would give me an error. I looked into GRUB2, but it's a little over my head. Is this idea of a portable OS possible right now, or should I just give up?