from the github wiki:

Rough VM size estimates:

IE7: 13GB IE8: 8.4GB IE9: 13GB Currently, the script will leave the compressed RAR files in place, which means you're looking at something like 45 freaking GB if you don't prune them manually (in ~/.ievms/vhd/). This wasn't a big deal for me on my company workstation, but kinda sucks on my Macbook Air, so I'll be adding a cleanup option shortly. You probably don't need to keep the compressed files around anyway since we take a snapshot like you mentioned.