Last week I downloaded the IE7 Beta 2 Preview Release.
It's not horrid, although the IE team really drank the MS Office 12 no-standard-toolbar Kool-Aid, so what you have instead of named dropdown menus evenly spaced across the top of the window is dropdown menus coming out unlabeled icons in random places all over the UI.
Asa Dotzler has a nice side-by-side comparison of IE7 versus Firefox that gives a good, detailed breakdown of this IE7 Preview.
To install it, by the way, you still have to reboot. Of course.