I just changed my Avitar to show my GTS250 that I just finished customizing. I used MS Paint to crop and then did a Strech and Skew at 60% each time till I got the photo small enough to fit the parameters. If I had realized it had to be so small I would have done a 20% 1st. The pic has to be 20k and only 128x128 pixels. I hit the 20k files size but the pic was still over 300 pixels.
I think it still looks good enough that you can tell there is no shiny chrome to slow me down.!!
To post pictures I download them off the camera then use paint to do a 35% x35% stretch and skew to get it under the 800 x800 pixel size limit.