I am working for very big insurance company.

Presently the application for policy administration is a client server application written in VB 6.0 with certain DCOM service running on a Windows 2000 Server. Around 3000 concurrent users are there.

The client application handles large amount of data. Also there is a business process for premium calculation. The calculation is complex, lots of data base operations and mathematical calculations. Presently these process run on client workstation.

How to migrate such an application ? How to design it?