Direct link for your model on the Dell web site:
http://support.dell.com/support/downloads/driverslist.aspx?c=us&cs=19&l=en&s=dhs&ServiceTag=&SystemID=PLX_PNT_CEL_GX270&os=WW1&osl=en&catid=&impid=
Look at the last item: Video
The one you need is probably the second: ATI - Driver
Applies to: 128MB PCI-Express x16 (Dual VGA or DVI) Radeon X300
If you have an Intel video, then you need the third one.
If it's a nVidia video, you take one of the last two.
Download the one matching your video card and execute it.
Those are simple EXE files that you only need to execute. The process is mostly automatic.
Electro, June 2011