Since the official enterprise launch in November 2006, business adoption of Windows Vista has crossed over 600,000 licenses in India. Giants like Infosys, TCS, Satyam, NIIT, K Raheja Corp, Symphony Services, Siemens BPO, Macawber Beekay and Larsen & Toubro have migrated to Vista
After the initial bout of mixed responses, Windows Vista has ended up making a dent in the Indian market.

One problem faced by Microsoft was that potential users had often formed a judgment of the OS without even using it. The fact is that Vista runs beautifully on new hardware, however retrofitting it onto older XP boxes is not a great idea.

Although there was no specific compelling reason to go in for such migration, it was done for the simple fact that Vista is the future of computing.

Source :  http://www.expresscomputeronline.com/20071001/market04.shtml