Check the graphics drivers. If there isn't an updated driver from Dell themselves, then go to Nvidia directly and try to get an updated driver from there. If that doesn't work, then try some other drivers...
This site has tweaked drivers that get you great visual quality as well as increased speed on most games. I usually use these and they seem to work great for me on almost every game I play. Just make sure to get the
mobile Nvidia drivers, rather than the regular ones, if you pick them up from here.
http://tweakforce.com/