Even I'm looking for a similar solution. We are using the Websense Cloud Web Security for Web Filtering.
1- Our ASA sends the RST , ACK packets back to the host who request the "microsoft.com" webpage.
2- Applications like Skype, TeamViewer doen't work as usual.
3- Windows 7 and Microsoft Office 2010 Activation doesn't work anymore.
Hope someone in this forum will help.