From a review of an IE7/Win beta:
At present, IE7 has a problem rendering some Web pages. According to Microsoft, this is caused by the sites, which need to update their detection code for IE7.
Standards-compliant pages don’t need browser detection. (And someday they won’t need browser hacks, either.) What the sites need to update is their markup.
Additionally, a request to Windows
Longhorn Vista testers: If you’re going to “leak” anything, please “leak” screenshots of IE7 in use with highly-standards-compliant sites; with enormous fonts; with Unicode test pages and severely complicated non-Latin scripts; and with MathML. Do please also show us what happens with large numbers of tabs.