One of the guys I work with told me about running the Microsoft Office Communicator in Linux. Its actually quite easy to install. Simply go to The Sipe Project website on sourceforge and follow the instructions. For me it was dead easy.
- Add a couple of sources to the /etc/apt/sources.list file ( deb http://ppa.launchpad.net/aavelar/ppa/ubuntu jaunty main AND deb-src http://ppa.launchpad.net/aavelar/ppa/ubuntu jaunty main)
- Run an apt-get command to install it. sudo apt-get install pidgin-sipe
Once the install is complete you can now add Microsoft LCS/OCS as an account type in the list. Simply fill in your creds and you are off to the races.