Hi Fred,
I have used vb for front end but only with allen bradley but i do know that you can use it also for siemens S7,it would just be a different server (probably mpi).
I have used the vb to drag data from a plc-5 and dump it into an access 2000 db.
You could drag the data into a vbapp using dde depending on the speed you require then write form vb into your database.I have some test code i done for access, if you e-mail me i will send it to you.