When you use 'define:' on Google you can get more than one result from different web sites. Live Search only uses Encarta and shows search results as well.

If I am looking for a definition, I want to see the different ways it can be interpreted. Also, I don't want search results as well (if you type 'define:' you are specifically wanting a defintion, not to do a general search).

So Google is the best for me.