In Windows 7, you can personalize size of text and other items such as icons smaller or larger using display options.
Click on Start menu -> Control Panel –> Appearance and Personalization
Under the Display section, click on the Make text and other items larger or smaller.
This would display the following windows with options for changing the size Smaller (which is default), Medium and Larger.
After the changes, you must log off from the computer to apply these changes.