Originally Posted by towny

All browsers use the same protocols for sending and receiving data, AFAIK. There's no reason why sending secure data through a Mozilla-based browser should be less trustworthy. If anything, it should be more secure as hackers and phishers tend to concentrate their efforts on cracking IE because it is the most popular browser.

The only problems you are likely to face are websites built by lazy developers that can only handle IE for Windows. It's best to keep a copy of IE lurking on your machine for these occasions.