If you go to this link, you will see the x1600 is a low end card:
Graphics Card Hierarchy Chart - Review Tom's Hardware : Best Graphics Cards For The Money: Jan. '09
You'll still be able to play most games but on a low graphics settings. To get the most out of your graphics card download and install the CCC package from ATI:
Graphics Drivers & Software
Once that is installed download and install these two updates:
DirectX (You need this whether you running DirectX 9, 10 or 10.1)
C ++ for Vista 64 bit
Once the last one is installed, reboot your pc.