Are you going to be multi-booting these other OSes with Windows, or are they going to be installed as VM's?
Depending on how many you'll be installing, 60GB is quite small and will install just about 5 to 7 distros with minimum installs. Again, it all depends on what you'll be doing. I have about 13 VM's with several distros installed in about 120GB, but then again, I don't have any additional apps installed in any of these.
You can find detailed info and download links for almost all of the distros at
http://distrowatch.com.