I did manage to make the trackpad work. You need to install trackpad++
(http://www.techspot.com/downloads/4967-trackpad-control-module.html), it will enable the trackpad driver on boot camp. After you install the trackpad++, trackpad++ will complain something. ingnore it. You should be able to enable trackpad. And you can now even uninstall the trackpad++, the trackpad will sill work.
brightness, what graphics card are you using? It might be due to the auto adjusting brightness running there. You can go to your power options, edit the one you are using (Change plan settings >> Change advanced power settings) and look for Batteries >> Enable adaptive brightness and disable the one you are using. After that, the scrollbar for adjusting brightness in power options should work again.
AUDIO FIX
I experienced zero audio output from my iMac's speakers with limited output using headphones.
Insert the installer disc for Snow Leopard while in Windows
Open the "Bootcamp" folder
Open the "Drivers" folder
Open the "Cirrus" folder
Double click and install the "CirrusAudioVista64" driver (or what is applicable to your system)
Restart your computer
If these steps don't work, uninstall the current driver by going to your Device Manager in Control Panel.
Download the Macbook Pro Cirrus Logic CS4206A Driver from our server.
Again, do not worry if you are running Windows 7 or Vista. (As a request, please do not hotlink this file anywhere else or our server will automatically remove the file from server.)
UPDATE: For newer Macbooks, you might need a newer driver which is availble here
Read more: http://realitypod.com/2010/07/macbook-pro-no-sound-in-windows-7-final-fix/#ixzz1 t4vwRCzv
http://realitypod.com/2010/07/macbook-pro-no-sound-in-windows-7-final-fix/