Each server would need 50 CALs (based on your example and Per Server
licensing [as opposed to Per Seat]), but you should always consult your
Microsoft Account Team representative when uncertain about licensing issues.
They can either answer your licensing questions or point you to the correct
party that can.
(P.S. - you may want to consider Per Seat licensing)
* DISCLAIMER: I am not a Microsoft Licensing Expert (and neither are you) 
--
Ryan Sokolowski
MCSE, CCNA, CCDA, BCFP
Avanade
http://www.Avanade.com
"A troubleshooter's best tool is the Event Viewer and understanding the
events and messages contained therein."
This posting is provided "AS IS" with no warranties, and confers no rights.
"Joe" <Joe@discussions.microsoft.com> wrote in message
news:2B1C3E4E-E520-4D6C-8ED1-4461BD6F3D82@microsoft.com...