There is a way of running several versions of Internet Explorer on one PC without resorting to dual booting. Details at Insert Title Web Designs. It looks like you can finally run IE5 on Windows XP for testing your HTML/CSS code.
The method is very simple and it illustrates the fact that Internet Explorer is not completely integrated into Windows. There is a set of
zipped files available. I wonder why developers were never told about this?
Update - Jan 9 2004: Downloads now available at: Skyzyx downloads - Internet Explorer versions 3, 4, 5 and 5.5 available