Album Art Files

How do I stop Windows Media Player 11 from overwriting MY album art? I have
unchecked all options to keep WMP from accessing the internet but it STILL
overwrites MY files. I don't want the lame 200x200 garbage that WMP thinks
is adequate. I have 600x600 graphics that look very nice. I remove all of
the "albumart*" files from my music folders and I delete the "folder.jpg"
file. I then copy in my own graphic and rename it to "folder.jpg" and set
the +R +S +H attributes. It's fine for a while but then I notice that ALL of
MY graphics have been overwritten by the same 200x200 garbage I THOUGHT I got
rid of earlier.

How do I stop this from happening? Or, more appropriately, WHY do the WMP
engineers think they know better than me about what album art I want?