So we have Enterprise edition 4.0 with 40 cal (1-20 and 2-10 CALs)

I just read this thread about the free BlackBerry Professional Software 4.1 for Microsoft Exchange and am now downloading it.

Can this be installed on the same on the same server as the enterprise edition?

BTW, we are planning to upgrade the 4.0 to 4.1 (eventually 4.2) in the next 30 days.
Thanks in advance.