Most suitable SQL server 2008 CAL licenses when running client software on a Remote Dekstop Server?

Hi,

We have a Remote Desktop Server where users are running a Microsoft Access Project client. This client connects to a SQL server 2008 back end database.

My question is to check whether it is best to purchase SQL server 2008 CAL device or user licenses in this scenario.

We have about 100 staff.

Thanks in advance

Paul