Errm, what's your soundcard got to do with it?
You need to ensure you have tyhe latest drivers etc, for you graphics adaptor.
You say it works ok with a 17" monitor - do you mean it works ok at 1280x1024? If so then it may just be that you have the wrong refresh rate set.
Right-click blank area of screen, choose properties
Go to the Settings tab
Click advanced
Go to the monitor tab
Set the refresh rate to 60 Hertz .
BTW when I got my 19" Samsung, I made the mistake of installing the software that came with it, which completely screwed my machine. After reverting to a restore point, I found that it works perfectly well without the software.