I've been using the latest MSN Desktop Search with the MSN Toolbar.  The latest version adds tabbed browsing to Internet Explorer, but I turned it off.  Similar to when I spent several weeks with Firefox, I just didn't feel comfortable with the tabs.  I'm just too used to ALT+TAB and ALT+F4 to navigate.  I know CTRL+TAB and CTRL+F4 will do the same, but why bother?

Anyway, the Desktop Search is excellent and I've loaded up many more IFilters to expand it's capabilities.

I'm wondering if a IFilter exists for browser history and the registry - although I don't know if search UI would be able to take advantage of them.  More details to come.