Sound problems with bootcamp / windows vista

I am fairly new to mac books and i just got a Macbook Pro 15".
Bootcamp came standard with my Mac and so i used it to install Windows vista. I can't get sound to work when i boot it in vista and ive tried almost everything. I've tried installing the realtek driver but it says that the file is broken or something like that and so i still can't get any sound. I read something about upgrading Bootcamp to version 2.1 but it says that my bootcamp version is 3.0.2. I've searched all over for the solution but i cant find one.

Any help will be greatly appreciated.

After you finish installing Windows, you'll want to pop in your Mac OS X disc into the drive while running Windows and install the Boot Camp software package. Do not attempt to manually install drivers.

Once this is complete, run the Apple Software Update from the Start Menu => All Programs and allow it to bring the Boot Camp driver package up to date. Sometimes Windows may warn you about unsigned drivers, be sure to allow them to install anyway.