Internet Explorer 8/7 has security feature called "ActiveX opt-in" that blocks controls without aproval even if the contol was installed by usual installer executable. So our plugin ActiveX installed by current win32 installer is blocked BY DEFAULT.
see http://msdn.microsoft.com/en-us/library/bb250471.aspx
(User could manually approve control; or the web page showing etoys project could be set as "trusted zone" in Internet Settings)

Win32 installer needs to write registry entry for preaproval.
I verified that the plugin works without manual setting by writing registry entry mentioned in the MS article.

IE7/8 have been pushed to even WindowsXP user via Windows Update. So this fix has become more important.