Magnifier is a good option if you want to temporary see something in bigger size but if you want to increase size permanently, Windows 7 allows you to increase the Windows text and other objects by 125 and 150% of the default available. Go to Control Panel\Appearance and Personalization\Display and set the magnification.
However there is only one catch here. The increase in display text and objects might make things not to fit in the screen resolution. So make sure you have high resolution set for this.