OK first of all, this whole layered/tiered model of designing programs is quite new to me so apologies if I'm using the wrong terminology anywhere (and please correct me).

I'm writing this job logging system (yes still, I had a month off ok! ) and I was originally planning to make it work like this:
WPF client application accesses SQL Database but also uses WCF service on a server for some central features such as sending email and tracking scheduled jobs.

However I am now thinking of making it more like this:
WPF client application requests data from the WCF service and the WCF service does the reading/writing from the database and returns the results to the WPF app.

So in effect I believe this makes the WCF service my data access layer, so all of the methods that access the database that would have originally been in my WPF app will now be methods in the WCF service (that are exposed via contracts etc).

Does this sound like a decent plan? I'm a little concerned about the scalability, I mean I dont know how well a system like this would work if I had 50 workstations running this WPF app that were all constantly running these various methods from the WCF service. The WCF service will be hosted within a windows service by the way and will be using TCP as the transport method.

Just looking for some thoughts/advice on how to implement something like this and whether or not its a good idea.

Thanks
Chris