Vylar Kaftan

Since I never bother to change my LJ icon, I would like to use my professional picture. It’s located here:

http://www.vylarkaftan.net/about-me/

It’s also located as a file on my computer. Every time I try to upload it (either cropping it square, or not) it comes out fuzzy.

Anyone know why? Can anyone help me do it right, either by telling me how or (if you have good tools) just helping me do it?

ETA: Thanks, Peer! How does this look? It’s much better than my attempts.