Q:

windows 8 phone development possible under windows 7?

is it possible to develop windows 8 phone applications in windows 7 with vs.net 2010?
Or do I need to upgrade to windows 8 altogether?

A:

Windows Phone 8 development possible under windows 7?

No, Windows 8 64-bit and Visual Studio 2012 are required.
Windows 8 Pro is also required to run the emulator (along with a processor that supports SLAT).
Source: http://www.microsoft.com/en-us/download/details.aspx?id=35471

