Few days back, Vijay sent a mail to an internal customer on the platforms/OS which MTM 2012 supports. I am just pasting the contents of his mail here as it is useful for everyone.

Supported Operating Systems

•Windows 7 (x86 and x64)

•Windows 8 (x86 and x64)

•Windows Server 2008 R2 (x64)

•Windows Server 2012 (x64)

Supported Architectures

•32-bit (x86)

•64-bit (x64)

If you are using the test agents to run automated tests on environments, the agents do support XP.