Just wondering what kind of processing power am I looking at for a business with less than 50 people?

I was asked to think ahead and come up with possible server upgrades that I might need when we switch from Netware to Linux.

We run GroupWise with the Datasync as well as FTP / Bordermanger (which will be replaced) as well as small web site and File storage for Revit / AutoCad drawings.

We were thinking of going the virtual server route but how much ram and processing power does that take?

Just wondering, never worked with virtual servers.