You may want to install IE 5.x, but keep Netscape as your default browser.
In tip 1128, I explained how to prevent IE from asking to become the default browser.
You can also prevent IE 5.x and Media Player from stealing the file associations associated with other programs.
When starting IE 5.x setup, click Advanced in the Components Options dialog box. Select the Don't associate file types option.
NOTE: With this option, IE 5.x will only setup associations for un-associated file types.