While Rojash is correct, you could also increase the resolution of your screen.
Right-click on your desktop and click properties. Click one of the tabs at the top of the window that's just appeared (last one I think), and you may find it's set to something like 1024x768. Increasing this will make everything on the screen smaller.
You can then increase the font size and icon size, if you need to. But web pages that were previously wider than your screen will now show in their entirety.
Also, you can get some mice (I have a Logitech MX1000 that works nicely), with a scroll wheel on the top that tilts left and right too. This makes it easy to scroll vertically as well as horizontally, without moving your hand much (basically just your index finger).