BRL,
You can make Opera your default internet browser and just use IE when Opera does not display the page properly. That way you get a solution that is best suited to your needs.
When it comes to email, I use
Netscape 4.79. It is a very good email client and it is so old that most viruses do not target it.
For the business we use
Eudora Pro, we have been using it since it was first released in the early 90s. It is an excellent email client for managing the 100s of emails the company gets a day.
My wife, for home use, really likes
IncrediMail. It is a great program for sending fun emails.
Take Care,
Richard