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

Here is this cool script that works for all old browsers:

Note: If the visitor ignores the advice, it won't appear again for some time.

More can be found: here