I took the hard drive from a T42 with a 14 inch screen and put it in a T42 with a 15" screen. Now I have a 14 inch desktop on my 15 inch screen! How do I resize the desktop to actually fit my 15 inch screen? I can't seem to find any way to do it. If it was a separate monitor it would be easy but since this is a laptop it's not quite so simple.
Since this is now running on a different system, be sure to update the video drivers to those appropriate to the new system since it is possible that it has a different graphic chip.
Try changing the resolution:
Right click on a blank area of the desktop
Adjust the slider to change resolution to the setting that fills the screen and select OK