Yes, you can upgrade it yourself. Just find out what your graphics card is and then search for free downloadable graphics drivers for your graphics card on
www.google.com. Than once you find the correct drivers for your graphics card install them and the restart your computer. Then your done. If that dosen't work than you need a new graphics card. I wouldn't go with anything less than a 256MB graphics card.
To adjust your video settings right click on your desktop and a small list of options will pop up. Click "Properties" and a new option window will pop up. Then choose "Settings" in the new window that poped up and in there is where you can change your video settings.