Note that if your text is anti-aliased you're going to want to set matte to the colour of your page background (or if your background is an image, perhaps set the matte to an average colour of the image) because there's no anti-aliasing with gifs

PNGs have support for it I think, but PNGs aren't too widely accepted yet I don't think.
If you can do it without losing much quality, simply turn text anti-aliasing off for your text layer and then save without a matte at all. Then it'll work on all background colours
Ex: