Windows Remote Assistance - A life saver in Vista!!

About Windows Remote Assistance in Vista. You have a colleague who wants to explain some issue he has, and he has created a scenario which he wants to show to you. He needs your quick assistance and you are finding it really difficult to understand what is happening. So, you decide to see his desktop (issue). The problem is that you don't want to go physically to his cubicle, because it is geographically seperated. How will you proceed??