How can I show a message to IE6/IE7 browsers to upgrade to IE8 and have IE8 not show the IE7 warning?

Question

I want to only allow users with IE8 (not IE6, IE7) or another browser to access my site when logged in.

I followed: http://code.google.com/p/ie6-upgrade-warning/ But

Answer 1

Rather than try to force IE 8+ mode, I use a combination of conditional comments and a simple javascript check. The document.documentMode property was added to IE in version 8, so if it exists at all (regardless of value, though it HAS to be 7 with this code) it means we're in compatibility mode and should not show the warning: