Hi Rajiv,

Take a look at the Virtual Earth (VE) interactive SDK --

The Virtual Earth Interactive SDK

This is most similar to Google Maps. The other option would be the MapPoint Web Service, but if you were using Google Maps before I think you will find VE easiest. Also, you can get started right away without signing up for developer credentials (like you would have to with MWS).

By the way, why are you switching? Perhaps that will help us help you.

Eric