I don't understand why anyone want to install anything on the pc. Hate those idiotic bulky synchronization software like itunes or nokia pc suite, which do very little but garbage every inch of your system, esp. under Windows.
And now you talking actually new drivers and even more software!!

Why not go the orthodox way? All we need to do is setup a streaming jpeg/mjpeg server on the N900. The server should grab images from the camera and mic and stream them as mjpeg (or simply put as jpegs).
Then, on the PC you just use your video programme of choice, specifying the address of the remote camera (like, http://n900-ip/streamort or http://n900-ip/cam.jpg) and you're done. A lot of IM and Surveillance programmes support remote cameras.
This will make the project fine and platform-independent.

If you want it wired, then you just mount n900 as NIC under Win or Linux, the same way as for wired SSH over usb.