Win 7 and Office Communicator 2005
I have talked about few of my experiences with Win 7 so far here, here and here. In general the experience so far has been good and applications either work as is or by setting the compatibility mode appropriately.
However with Office Communicator 2005 there is an issue in desktop andapplication sharing. OC 2005 uses Netmeeting as the underlying mechanism for sharing and Netmeeting isn't supported Vista onwards. The OC 2005 planning and deployment guide also only lists OSs till XP as supported and Vista and Win 7 aren't. There was a hotfix released later by MS to support Netmeeting on Vista, but this isn't supported on Win 7.
So with Win 7 you can use OC 2005 for chatting, but can't do desktop and application sharing. You need to either upgrade to OCS 2007 and OC 2007 or use other tools like Live Meeting etc.