I very much recommend that you do your development with Mozilla. Go grab firefox 0.8 at http://www.mozilla.org
IE can be sleazy sometimes, and will render things "correctly" even when you've made mistakes. You could call this a benefit or a detriment, depending on your perspective.
If you get your page looking right in Mozilla, there's a good chance it'll look right in IE too. So usually I'll be checking my progress in Mozilla, and then when I'm about finished I'll give it a look-over in IE. That seems to be the most efficient way to go about things.