Of course there is the question of why you don't just use remote desktop on each of the machines.....

I have a similar issue and have found that MS Live Mesh, and I think that it is a great solution to your issue. It will allow you to control any PC in your mesh from any other PC, and remotely via a web browser. You can easily share documents on each of the machines as well, a nice solution for backing up your own data. Finally, you have he software works on Windows and OSX; however, you can only sync files to a Mac. It would appear that they are working on being able to control a Mac remotely.

It's not a good thing that you can't create an account, or even log-in to this service. I don't think that they are going to get many new people if their web site crashes!