Ever Since Windows 7 has come out we’ve been seeing a lot of customer interest in running the vSphere Client on it. The same goes for Windows 2008 R2. The trouble is, Microsoft changed the .Net loading mechanism in these releases, breaking our vSphere Client.
We have just posted a Knowledgebase article which outlines how to deal with this change and make the client work.
One caveat: watch for the warning that one of the workarounds is not officially supported.