You need to go to the manufacturer web site for the desktop/laptop/or graphic card (depending on what system you have) and download and install the latest video driver.
How do you mean dull?
Resolution has nothing to do with brightness which is what you're implying.
If you right click on the Win 7 desktop and click screen resolution what resolution does it say?
Do you have any other options when you right click. I have a GTX 670 and mine says Nvidia Control Panel and I can change settings on that.
Lastly, can you change anything on your monitor?
And as RealBeast says, what graphics card do you have?