Why SQL on Win7 not accessible to network when using Remote Desktop?

We run a small network using a Win7 workstation as file server. This file server uses SQL2008 to serve data to other Win7 computers on the network. Sounds fairly simple, but when the user of the workstation/server works on Remote Desktop connection to an external customer’s computer the SQL served data is unavailable to our network users. Is there a work-around for this?