well, the link pic in the post is 150x112, and the full size you uploaded is 320x240
you gotta squeeze the living crud out of it.

Try to get it to 85 across or so, then try an upload to avatar.
try it scaled down to 1/3 of what you have now... then crop if need be
I had to whittle mine lil guy down to 64x64 to fit some other board, but now I can use him as an Icon

If you have the image larger, and maybe a not so compressed jpg, always mess with a copy of the original, dont scale a scale, or jpg a jpg if you dont have to. You lose too much acuracy, the old Copy of Copy problem.