Are you like me, Windows 7 x64 (or another x64 windows OS) and you want to install Office 2010 x64 instead of the 32-bit version but you are trapped because your company still uses Office Communicator 2007 R2. With the help of some trusty Google searches I have found steps to accomplish this.
Install the Lync 2010 x64 client to your Windows 7 machine. You can download a trial version here. However I would recommend that you get it from your local administrator, and double check to make sure they will not kill you doing this to a company machine.
Once install add the following to the registry otherwise you will get a versioning check error:
Note: Notice that we are still using DWORD on x64 instead of QWORD. At the time of this Article you have to use DWORD.
Value: 1 (00000001)
Once done, start Lync 2010 and you should be good to go.