How many fonts is too many?
When you can no longer install more fonts you definitely have too many. As a general rule of thumb, you can expect to run into installation problems with 800-1000 or more installed fonts. In practice, you'll probably encounter system slowdowns with fewer fonts. There is no magic number. The maximum number of fonts will vary from system to system due to the way the Windows System Registry works.
There is a Registry Key within Windows (for Win9x and WinME versions) that contains the names of all the TrueType fonts installed and the paths to those fonts. This Registry Key has a size limit. When that limit is reached, you can no longer install more fonts. If all your fonts have very short names you can install more fonts than if they all had very long names.
But "too many" is more than just a limitation of the operating system. Do you really want to scroll through a list of 700 or even 500 fonts from within your software applications? For best performance and ease of use, you'd do well to limit installed fonts to fewer than 500, perhaps as few as 200 if you're using a font manager as described below.
Can I delete any fonts I don't want?
Yes and No. There are certain fonts required by your operating system and specific programs that should be present. Fonts that you use day in and day out should also remain. Graphics Software Guide Sue Chastain has an excellent list of required and default fonts for Windows and for many common programs.
Windows Fonts That Should Not Be Deleted
Before you begin deleting fonts from the Windows Font folder, make sure you save a copy of that font in case you discover you really want it or that one of your software programs requires it.
But I want ALL my fonts!
Can't bear to part with your fonts but Windows is overloaded? You need a font manager. A font manager simplifies the process of installing and uninstalling fonts and allows you to browse your entire collection - even uninstalled fonts. Some have features for printing samples, automatic font activation, or cleaning up corrupt fonts.
In addition to font browsing, programs such as Adobe Type Manager or Bitstream Font Navigator allow you to create font groups or sets. You can install and uninstall these font groups when you need them for a certain project. Your core or most used fonts stay installed at all times but all your other favorites are tucked away ready to be used at a moment's notice. This provides you with ready access to 1000s of fonts while keeping your system running smoothly with a manageable number of installed fonts.
Type and Font Software Tools for PC Windows and DOS
Software for font management, designing type, and printing samplers under Windows or DOS.