Here's some web pages that should help you - I'll check back later this evening to see if they helped.
http://www.microsoft.com/enable/trai...ppearance.aspx

vista-
http://www.vista4beginners.com/How-to-change-font-size


the advanced dpi setting - click the little ruler to slide it to what looks best - right now mine it is set at 104%

http://helpdeskgeek.com/windows-xp-t...on-windows-xp/
[DPI (dots per inch) settings control the images resolution on your computer, the higher the DPIs the sharper the image will be. You can change the DPI settings to fit your liking. On windows XP right-click on an empty area on your desktop and go to properties>settings>advanced]

microsoft page about it-
http://www.microsoft.com/resources/d....mspx?mfr=true