In the profile settings it's possible to upload an animated GIF directly from your harddrive. I've tried doing this, but the GIF doesn't animate. I suppose I could do as DickyD says (which obviously works, incidentally), but I prefer Admin's suggestion of uploading from my own PC.
Talking of which...
While I'm uploading and generally trying to find out why the GIF doesn't animate, I received this message. Probably of more importance to Martin...
"Sorry, the copyright must be in the template.
Please notify this forum's administrator that this site is using an ILLEGAL copy of SMF!".