If you're using pre-XP Windows, having a bunch of fonts can really slow your computer down because the programming doesn't handle them well. If you're running XP and above, a bunch of fonts installed in your PC really doesn't effect the PC at all. HOWEVER, it can make photo editing programs open REALLY slowly because they have to install all those fonts as they open each time. A font manager can really help keep your PC cleaned up, help your photo editing programs run more smoothly, and can help you organize your fonts, making them more useful to you.
The Font Thing, AMPViewer, FontHit (which is what I use but does not work with Vista), ACDSee (can work as a manager), are all free Windows font managers. They allow you to keep fonts uninstalled that are not primary to your system (
click here for a list of default fonts for Windows). The managers also allow you to create sub-folders to organize fonts into. If you have a lot, it can be a pain to browse through the who list trying to find edgy, stamped grunge fonts. So you can create a folder of just those kinds of fonts, then go to that particular folder when you're trying to install the font you need. Then quickly uninstall it when you're done! I have folders for CU fonts separate from non-CU so if I'm doing any design work, I know which fonts are OK for CU applications and which ones aren't. I keep handwriting fonts separate from typewriter fonts, etc.
Janet did a great article on it at
The Daily Digi if you want to read more.