ActiveX is a technology for extending what Internet Explorer can do. Some Web pages use ActiveX controls to display animations, play games, verify the integrity of your Windows installation, or do other things that the browser couldn’t normally do.

Standard users can’t install most ActiveX controls–you need to be an administrator. If you only give your users a standard login, they might run into problems using ActiveX. To enable users to install specific ActiveX controls, you can use the ActiveX Installer Service.

The ActiveX Installer Service is disabled by default (well, it’s not even installed). To install it, follow these steps:

1. Click Start, and then click Control Panel.
2. Click Programs. Then, click Turn Windows Features On And Off. A UAC prompt appears.
3. At the Windows Features dialog, select ActiveX Installer Service check box. Then, click OK.
4. Restart your computer.
5. After the computer restarts, you need to set the ActiveX Installer (AxInstSV) service to start automatically. Click Start, right-click Computer, and then click Manage. Expand Services and Applications, and then click Services. Right-click ActiveX Installer (AxInstSV), and then click Properties. Click Startup type, and then click Automatic. Then, click the Start button, and finally click OK.

Now that you’ve done that, nothing will behave differently. To use it, you must enable the “Computer Configuration\Administrative Templates\Windows Components\ActiveX Installer Service\Approved Installation Sites For ActiveX Controls” Group Policy setting and add each URL you want to allow ActiveX controls for. For the value, you can typically just go with “2,2,1,0″.

For more detailed information, read Gabriel’s post on the same topic (based on a pre-release version of Vista).