My study lab.

This is how i have my study guide setup.

I don't have the money or space to buy 3-4 PC and set up my own network, so i use VMware work station, i have it installed on my laptop and on my desktop. The main reason i have it on my laptop is so at lunch time at work i can still mess around with stuff i am learning.

Desktop spec:

Intel core 2 duo 2ghz
4gb RAM
500GB Hard drive

Laptop spec:
Intel core 2 duo 1.66ghz
2GB Ram (going to upgrade to 4 soon).
320GB Hard drive

VMware is really easy to use and in my opinion a little better than Microsoft's Virtual PC, but you do need to pay for it, whereas Microsoft's Virtual PC is a free download.

VMware site is www.vmware.com
Microsoft Virtual PC site is here

There is also virtualbox an open source alternative, which is also supposed to be quite good, although i haven't used it. www.virtualbox.org