I honestly haven't had any issues with images either on this site or anywhere else.
I'm using noscript,Adblock plus and Betterprivacy.
I'm using FF v7.0.1 and running it on XP 32bit (on a really old single core rig).
There's a Java update (for XP) I haven't got around to, but I can't think of anything that could be causing your issues
Yeah, FF has been eating chunks of memory lately (last time I noticed I think it was around 380MB).......it's probably best to shut it down and clear cookies/cache if you're running it for extended periods.
Besides this issue I have no real complaints.