Just a note: if you run Internet Explorer 6 from machine with Visual Studio .NET installed,
the browser sends this user-agent string:

Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; )

To remove .NET part open this key in registry and delete value:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\5.0\User Agent\Post Platform