For my private projects I decided to make it work in FF and in FF only. The reasoning is: I am the one who uses it the most, so it has to look good in my browser.
At work we make the site standards compliant first, so it will look acceptable in FF and Opera and Webkit (Safari). Only then we create an extra style sheet for IE which has all the needed hacks. Often we have several IE-specific style sheets. So, we don't have separate versions of the page, but only of the style sheet.
And we don't do Javascript without
jQuery.
jQuery is a godsend, and every time I use it I am grateful to the developers because I actually have FUN creating websites.