Hi everyone, i was wondering if it is possible to purchase just the unity software, without the dedicated hardware ?, we have all our servers "virtualised" with a huge SAN, so adding a new virtual server costs us nothing, is this possible ?

I do not believe that's possible, no. Avid probably could not (and certainly would not) certify the stability of a Unity File Manager running as a virtual server.

http://community.avid.com/forums/t/56416.aspx

is a thread that basically covered your question.

Jay