If you had any doubt that Internet Explorer 8 beta 1 was released as a developer preview and wasn't really meant for general consumption, consider this: You can't access Windows Update
using Internet Explorer 8. If you try to visit the Windows Update page, you'll get a message telling you that you need to use Internet Explorer 5 or later.
Microsoft plans to add IE8 support to its software update page, but it's not available yet. In the meantime, you can get your updates by clicking the Emulate IE7 button in IE8 and restarting your browser.