What's the bare minimum for this? I want to have a very small HD, 10 gigs probably, to play with Gentoo Linux. Since I don't want to go through the trouble of redoing partioning my HD once again (ugh), I would rather spend some money and buy a seperate attached one. It doesn't matter if it's a 4200 rpm on of it the transfer speed will be horribly slow. I just want to learn Linux, keep up with the distros and the such. We use it all the time in the college's library where I work so it would benefit me from learning all I can about it. So what's the bare minimum I can spend and get to do this? I want to be able to boot from the HD w/o installing it in my macbook obviously. Thanks for any suggestions.