MS SQL License for ZCM Database

Hello,

we are planning to migrate ZCM database from Sybase Embedded to MS SQL 2008. I´m not sure which license is the best choice for MS SQL Server. At the moment we just have 200 Devices but after migrating to windows 7 there will be 3300 or more devices.

Which license model for MS SQL Server should we prefer?

Thanks
hackstes