Driver installation problem in Vista HELP NEEDED

I have a Vista Business 32bit OS and am hving trouble solving the famous 'no-sound' mystery.
I tried the simplest way of solving it:

1. Downloaded the Realtek AC'97 driver (as guided by some other forum: No sound with Windows Vista)

2. Tried installing by running up 'setup.exe'.

3. All was well till Vista came up with this message:
'Windows can't verify the publisher of this driver software' and had two options:-
-> Don't install this driver software
-> install this driver anyway

I tried using the 2nd option - nothing happened and the same message popped up.
The 1st option obviously quit the installation process.

What do I do? Can anyone please help me on this?? It is frustrating to have a computer without sound and nothing to be done about it..

Thanks!

Do you have a Realtek sound card installed?
If Yes, have a look here:

http://www.vistax64.com/sound-audio/64250-latest-realtek-hd-audio-driver-version.html