Wendy - I went back to IE after using Firefox for awhile because too many sites I went to were not compatible with Firefox. Otherwise, I preferred it to Explorer.
That was about a year ago - might be worth relooking at those sites that didn't work.
Do you know if Thunderbird has imap capability so I can get aol & netscape mail there?
And I have so much saved in Outlook - I'd be afraid to lose it.