Moved to Firefox 1.0 on my linux box as well my windows machine. Both installations rock. One major annoyance i had with each and every firefox upgrade is that my themes just stop working. I had to download the theme again every time i installed a new version. I had guessed that issue would go off with 1.0 , but the problem still persists. This problem is present in both my Linux and Windows machines, so what i doubt whether its my configuration thats the root cause of the problem. May be its just my favourite themes, but still its pretty nasty when i end up everytime having to search and download my favourite theme.