Firefox/Aol question

The majority of flaws in IE that result in a compromised system are related to surfing at websites that attempt to exploit IE's security holes while webpages load down to your system. These pages might have any number of scripting, Java or ActiveX based objects that are written specifically to break through holes in IE, so IE must actually parse these webpages itself in order to have an exploit occur.

So, no, from this perspective you aren't risking your system because of IE. But, there's a lot more to IE than just it's browser window. The browsing code in IE is shared in a lot of other parts of Windows - Outlook, Outlook Express, Windows Explorer... So be mindful of those tools and possible exploits related to Internet Explorer.

Also, if you do use the AOL window for AOL content and click on links there, I'd guess those would open IE windows, so just be cautious whenever you are in AOL content itself. You may want to ensure that Firefox is your default browser, as well, so that when a link is click from anywhere Firefox opens and attempts to get the page and not IE.