Our company is currently running R/3 release 4.6C. I am researching what it would take for our company to start using SAP XI. Is it possible to instal

EXPERT RESPONSE
XI will run as a separate instance. It is a middleware product that plugs in right between your current systems. Installing XI does not impact your SAP releases at all; it won't touch them.

So the question "does it need own boxes?" should be answered "Yes!" (actually it can run side by side on the same box as R/3, but as a separate instance, which is just like an own box).