I use Firefox now, and haven't found any problems with it.
However, I do expect to find problems. The programmers of Firefox uses the standard web based languages as do all browsers, including IE. But IE also uses "it's own bits" that are not standard, but nevertheless web page developers have to account for that as IE is the most common browser out there.
So, some web sites may not work properly with Firefox.
Having said that, it should not concern you. By downloading and installing Firefox, you will "not" be uninstalling IE, it will still be there available to you on your desktop, or in Program Files, etc.
So if you do come across a web site you normally go to that doesn't work as you expect in Firefox, just go back to IE temporarily and use that.
I am running windows 2000 with a D-Link 704P router. I have the latest version of Spy Sweeper and run it almost daily. I am using Norton AV.. and keep it updated all the time. I scan both incoming and outgoing email. I mostly use my computer for communication (chatting with family) and some of the game sites. I have greeting card newsletters coming in, and a few tech newsletter (the ones I HOPE to be able to understand) and for doing artwork. Can you tell me if most game downloads, greeting cards, etc. are compatible to firefox? and what problems one might run into with using it. Is it compatible to the IM programs? In what way does it operate in comparrison to IE...and what conflicts could one possiblly run into if one were using it? I know these are a lot of questions, but I am very leery of changing this "main" component. My IE is as up to date as it can be.