Although Explorer and Outlook have some nice features, they contain more bugs than Netscape. Using the help of Outlook Express causes crashes on 3 different computers! (using the "back" button)
I use Netscape 4.7. It is fast and stable.
But I give all my applications a lot of memory. (PS: Explorer has a memory bug, the longer you use it, the more RAM hungry it is)
Not a problem with Netscape...