I have a software and I cannot decide which approach would be the proper method. I blame on lack of experience!

So I have a Windows Service running in the background, and it's populating a database every 1/2 a minute. The Db is a flat file DB (Sql CE), which might/might not be replaced with a server DB.

Then there is GUI that needs to query the DB, and display the result in human readable form. Preety standard right..!

So here is my dilemma, would it be better for the GUI to access to DB directly to get/insert data, or connect to the Windows Service using WCF and make requests that way?
I should mention, the Windows Service would already have a WCF service running, to service a silverlight version of the GUI.
Thanks in Advance...