Notebook LCD Screen anomoly

I just changed out a damaged 15.4 lcd screen in an Acer 5630. The Brand New lcd screen is only displaying 640 x 480 and minimum color even though the computer (winXP) is set for 1024 x 768 with 32 bit color. I have gone through the process of resetting the resolution and color density and although it appears to work the screen doesn’t change. The display only fills about 3/4 of the screen. This is a first for me nothing should have changed the drivers. Anybody have any ideas?