Complex sentence: Windows Update requires Internet Explorer or a third-party web browser that uses Microsoft's MSHTML layout engine, as it must support the use of an ActiveX control to house the software that is executed on the user's computer.
Split into simpler sentences: Windows Update requires Internet Explorer or a third-party web browser that uses Microsoft's MSHTML layout engine. This necessity stems from the use of an ActiveX control to house the software that is executed on the user's computer.