Windows Vista introduces a great new method of easily and quickly changing your desktop icon size. If you want to make your icons larger, this is the tip you are looking for.
First, make sure you are viewing your desktop, then hold down the CTRL button on your keyboard, and then move your mouse Scroll Wheel up or down. If you scroll up, the icons become larger and if you scroll down they become smaller:
This resizing tip works in many other applications too, so if you find that the icons or text is too small, give this a try.