Not being a Gimp user I may be out of line here, but I do know that adding lots of font to windows is never a good idea. I just checked my font collection folder (1.3 gig) and I use a lot of them all the time with out slowing down anything. Most I know use decorative fonts for graphic applications. To use a font that is not installed in windows simply open the font file itself (.ttf) and minimize it to the taskbar, open the graphic program and when you wish to use that font it will show in the programs font menu. This works with Corel draw, Adobe CS, Photo Impact, Paint Shop Pro, but I don’t know about gimp as I have never used it. I also included a link for a great little free font manager.
The Font Thing
Browse installed and uninstalled TrueType fonts, viewing sample text, individual characters, and detailed font information. Easy font-management functions let you install, uninstall, print, copy, or delete any number of fonts at once. You can even store your own notes with them, filter them according to type (serif, sans serif, and so on), and group them into collections for convenience. This version lets you choose your font colors, set up drop-down lists of standard text samples, rename font files to avoid conflicts, and load fonts temporarily for use without installing them
[link="http://www.download.com/3000-2316-1519711.html"]http://www.download.com/3000-2316-1519711.html">Link
Robert