via Paul Thurrott:
With MSN Search Toolbar with WDS installed, IE gains the new tabbed browsing functionality, which is similar to tabbed browsing on other browsers, such as Mozilla Firefox. It includes a My Tabs feature that lets you easily bookmark a set of Web site addresses, each of which will open in individual tabs when selected. Also, the feature lets you open MSN Search results in background tabs, which don't disrupt the current window display.
I was skeptical of this update since I didn't really care for the last version. However, it looked interesting so I took it for a spin and it is pretty nice. One of the features I appreciate the most is how configurable everything is. For instance, you can configure the toolbar to use Google's search instead of MSN's search:
The tabbed browsing is also a nice feature. I can open up one browser and use tabs to open all my various web email accounts. Or you can search and open a bunch of different finds in different tabs for easy reference. I haven't tried the desktop search yet so I can't comment on that, but the search bar is great.