Virtual machine for testing Internet Explorer 7 & 8

"A virtual machine, like the name suggests, is like another machine, emulated (well, at least in this case. I'm ruling out VMs used by some programming languages, which are something else). As such, you will need to install one system per virtual machine, like if you were installing on a physical one.

There can be easier ways for you to try different browsers, however, like for example on this other question, about several versions of Internet Explorer on the same machine."