Did you download and install the Windows support software? When you ran Bootcamp Assistant one of the menu items was to download the Windows support software. You can run Bootcamp Assistant again and only select the option to download the Windows support software. Read the support software installation instructions carefully.
Disregard what I said above. I just noticed that you are running Snow Leopard. The Windows support software is on your Snow Leopard installation disk. Insert the disk while in Windows and install the support software.