Many people I know who spend time on the net and want to search, but don't see the difference in search engines, will just use the first one handed to them. This translates to lots of people I know using Yahoo, simply because one of the first things they did online was to setup a Yahoo Mail account - when they go to check their email, they are in Yahoo's environment so it's easy to search from there. Considering Microsoft's ability to integrate things tightly.. I'd imagine that the combo of MSN Messenger / Search / Hotmail and Windows could fulfil a lot of people's online needs a lot of the time - if they use the net primarily for chat, mail and light searching why not do it all from one place? Especially if the OS itself seemingly integrates these : )