You'll want VM's, IMHO.  As MaXe says, if money affords, the CPU's that support Hypervisors are best.  But if you're tight on funds, get the best you can for the buck.  Don't skimp, if you can help it.

cd82, nice I'm a little jealous. I want a new laptop, but I'm saving up more money. The one I have my eye on is really designed to be a gaming machine. I figure I can run what I really want to with that beast.

As for the netbook. I bought an eeepc one last year, I hate it. It's running bt4r2.

The screen is too small for any real work.
The keyboard sucks for typing on.
forget trying to run jtr on it.

It's a nice little toy, but not a good quick little hacking box like I hoped. really it spends most of it's time turned off with books and stuff stacked on top of it, and I only tend to get it out when I need to update my phone (triple boot between windows 7, ubuntu and bt4r2). I've used it for war driving a few times with my Alfa plugged and gps receiver plugged in to it. but beyond that not really as great as I thought it would be.

Just remember to lock down your BT sustenance. wither it's virtual or a direct install. Some simple things like disabling root log in from anything other then the console. Change the password. Set up a regular user account and go to root if and when you need to. Change the name of the box.

A friend and I were talking on twitter the week before classes started about how we were installing bt5, a friend that is the network admin at another school said he loved finding students running bt on the network. Which lead to a third friend jumping in and sharing her experience of that happening when she was new to BT.