Need to know Windows Licensing

Hi all,

I am taking the Windows 2003 Std edition for our one of the database as well as Domain controller server & i have the 50 users which are going to access this server daily for data
so i wanted to know CAL (Client accessing License) is needful for us by default win2K3 std will come with 5CAL and extra CAL cost is near about 1400 Rs.
so is it necessary to get 50 CAL’s more or Windows 2003Std with 5CAL will do?

Awaiting for your valuable suggetion.