How do I change DPI?

[LAPIII]

I'm trying to set up a program that requires that requires this. I must have recently changed this since I know have an issue with the start menu not being able to display all of the icons.

My PC is running Windows Vista Home Premium, my resolution is 1440 x 900 which is the monitors maximum

 

[dmroeder]

Right click on desktop and select "Personalize". On the left of the window that pops up you will see "Adjust font size (DPI)".