To increase fonts on entire PC, in XP (similar in W7 and 8), go to Control Panel>Display, and in the Appearance tab you can select Normal, Large, or Extra Large.
In similar fashion, you can select the Settungs tab of the abovememtioned menu, and set the screen resolution lower than it is now
Also in the Advanced button of the Settings tab, you can set the DPI to large - this makes the fonts larger in system popup windows like Clock, Task Manager, Display, Wireless, etc.