A problem with upgrading some laptops to Windows 7 & later is they can be a little too old for the manufacturer to care about providing driver updates so that everything works the way it should do after the upgrade.
One recent example I came across was upgrading a Sony Vaio VGN-SZ4XWM (PCG-6Q1M) from Vista to 7. Windows updates only finds a standard graphics driver that only lets the screen display in a size half the size it should be with two black bars on either side.
The Sony support page for this particular laptop only gives two supported drivers for Windows 7, but if you scroll on down you will see drivers for Vista. Although installing Vista drivers to 7 shouldn’t work it does in this particular occasion. There is a driver called nVidia Video Driver – 188.8.131.5254. Download this and install. Your screen will be back to normal size.