GIF Optimizer
Depending on the built-in optimization features of your image editor, this useful tool may be exactly what you need to put GIF images on a diet. By eliminating unused colors from the palette, less information is required to display the image, making its overall size smaller. For animated GIF files, duplicate frames are removed, which helps keep file size in check. Best of all, this is a free tool. While I haven't tested GIF Optimizer on WinXP, I have used it on a Windows 2000 machine, so it will probably work in both places. [Windows 9x/2k/XP $0.00]