How many CAL's do I have in my domain?

How is Licensing managed today in an AD domain? The current setup that we have is around 10 DC's, 4 Terminal Servers and multiple license servers??? How do I determine how many CAL's I have already purchased vs how many I need to purchase to be current? When I go to the most current DC and click on Admin Tools, Licensing, Prodcuts View  it reports:
Windows Server        Per Device or Per User Purchased-10499       Per Server Purchased-35           Per Server Reached-3

When I click on another server in the same domain, Admin Tools, Licensing, Prodcuts View  it reports:
Windows Server        Per Device or Per User Purchased-728       Per Server Purchased-32012           Per Server Reached-311

What if any of this information is correct? Can I even use this licensing tool to determine my current # of CAL's? Is there another tool I can use that will more accurately compute the number for me?


Background Information on my domain-10 DC's, 10 Sites, Around 600 Users, 700 XP Workstations, Multiple Server 2003 and Server 2008 Servers

I am at a complete loss on which Licensing Server I should go by. How do I determine which is the "MAIN" license server, how many license servers do I have in my domain? How many CAL's?

Thanks in advance,