Windows 7 is compatible with Microsoft Dynamics GP10. We can run Dynamics GP 10 on Windows7 as well as Windows Server 2008 R2 once they are RTM'd, expecting in October. Product teams for Dynamics GP have already completed the testing of the Windows 7 bits, according to Inside Microsoft Dynamics GP Blog.
The System requirements for Dynamics GP 10 is also updated with this information in the Additional information page.
Interesting news to know is that there are no plans to make it compatible with Dynamics GP 9.0 or before. So, Watch out, It's time for Upgrade to Dynamics GP10.
For more information, Refer to this article from Inside Microsoft Dynamics GP Blog.