I have a 2010 Dell XPS Studio Computer with an ATI Radeon HD 5450 Video Card. I have two hard drives for two different boot ups: Ubuntu and Windows 7. Since my upgrade to Ubuntu 12.10, my video card does not fill my 24" monitor. It was fine before the upgrade and my Windows 7 is fine. The only options I have in the display tool is resolution, and it is set to the max. How can I fix this?