Thanks Gif worked nicely, it went itsy-bitsy immediately.

I'm still struggling to get the 200x200 under 19 kB, though, but I'll figure it out somehow. I'm using IrfanView, and am trying different combinations of reducing colour depth (that actually made the file bigger), greyscale (ditto). reducing the dpi (no difference??), jpg-compression and converting to gif.

Feeling a bit stooopid here now...

... but I do have a new winter avatar