Multiple Browsers?

I have a W98SE PC I want to install multiple browsers on. Netscape 4.7, 6.2, IE 4.0, IE 5.5, IE 6.0 and Opera 5.0.I even found a WebTV emulator!

The reason is to do a test of my company’s web sites.

I’m not sure how to isolate the different versions of IE from each other. Any suggestions?