For an LCD monitor, set the refresh rate to 60.
Also make sure your power supply can run the video card a 5450 should not use much power at all, but if you have a weak or cheap power supply, can bring it over the limit.
Also, is that a new or used card? If used, it could have been damaged already. I've run into used video cards that don't work when the drivers are installed but work on the VGA drivers.