Looking through the forums, only one question appears more often than this one. It seems a good time to write this up.
If you want to know whether any particular version of Arbortext is supported on any particular version of Windows, check the Software Compatibility Matrix.
For example, here's the Arbortext Software Compatibility Matrix for 5.3.
http://www.ptc.com/appserver/wcms/standards/fileothumbredirect.jsp?im_dbkey=46355&icg_dbkey=522 (You'll need to log in.)
Here's how to find this document and others like it:
Go to: http://www.ptc.com/support/arbortext
(For now), in the right-hand navigation, there's a link for: "Reference Documents"
When you get to the search page: