Have you set the soundcard as your active device in Device Manager and associated it with your other programs?
It will be listed under Sound, Video and Games controllers - highlight your sound card and click Properties.
Did you have any form of audio control centre software as well as drivers?
If you go to the Creative website you should be able to download the Live Audio Center (correct) from where you can manipulate the sound output to your requirements.
You should also have installed the driver before installing the sound card and let Windows find the driver after a reboot.