Seattle-based Redfin said today that it has changed its underlying map platform to Microsoft Virtual Earth. The firm previously was using Google Maps for its map displays, and said in its blog today that it evaluated using Google Maps, Microsoft Virtual Earth, or to continue developing its own mapping technology, and decided to switch to Microsoft for the map platform. The new maps offer better performance, double-click zooming, and a choice between aerial imagery and map views. Redfin operates an online real estate service with coverage of Seattle and San Francisco.