I've also followed this to the last detail documented. 1 small fix, the name of the getbrowser.php file is getBrowser.php in the zip archive. On unix systems it can't find the file. Rename getBrowser.php to getbrowser.php and it gets further.
Tested on WinXP I.E 6.0.2600
and Win ME I.E 5.5
Very nice hack indeed, I hope the problems can be ironed out.

Good work.
Edit just noticed update...