Editing Favicons

Hey …

I am using a theme that comes with its own favico, which is very cool. However, I want to edit this theme (and maybe a couple of others) to create a new look for my site, and I will need to replace the .ico file.

However, I am on a Mac. I have both Adobe Photoshop 7 and Fireworks installed on my Mac, but neither one of them will open a .ico file correctly.

Does anyone out there know of a Mac program I can use to create or edit my own .ico file from another format, such as .jpg, .gif, .psd or .png?

Thanks!