Regarding the IE issues:
As I said, I'm on Windows XP. The IE version is 6.0 (SP2).
Now I don't think that I'm the ideal candidate for testing with the IE - personally I don't use that anymore. (But probably there are still users with IE 6.0.)
That being said, here are some problems that I have on my machine with the IE:
Screenshots of the main page:
With FF:

With IE:
- It seems that the general layout is not fully adopted with the IE. Probably some of the other problems are just a result of that.
- What's that "no hotlinking"? LOL (I'm not always getting this.)
- I can't reach most of the user settings. I have to type in the URLs directly (user, user/login, user/logout). If I mark the user box in the upper right corner of the MoviePosterDB, I see some leftovers of the normal text:
Some other examples with the layout:
On a user profile:

The poster pages:
- The transparency of the small png images doesn't work. But I think, that's a general problem of the older IE versions.

(You could set the background color in some PNGs. Don't know if that's worth it.)
Perhaps you can use some of that..