MSN's methods for search results rankings are not publicly documented but they are currently using what they refer to as the RankNet system which supposedly "recognizes" good results and lists them accordingly. The top results from MSN seem to be weighted in favor of somone searching in the context of current events and popular topics.

So, you will get different results dependent on which search engine you choose. Let's imagine we want to find information about robins, the northern hemisphere's harbingers of spring. We will try the same search on all three major search engines, just the word 'robin' all by itself, and see what we get.

Google - returned 219,000,000 results. At the top of the results page are three pictures of robins. The first search result is a restaurant chain with the word 'robin' in its name, then a site about 'Batman & Robin', a site about the actor Robin Williams, and fourth an encyclopedia entry about the birds referred to as robins.

Yahoo - returned 64,400,000 results. At the top of the results is a bookshop with the word 'robin' it its name followed by several news reports about celebrities named Robin. The first 10 search results have no mention of the birds but the next page of results includes an entry about states which have named the robin as the state bird and the 15th entry has information about the bird itself.

MSN - returned 23,251,356 results. At the top of the results page are two sponsored links about art prints and shopping for robins. The first search result is a manufacturer with the word 'robin' in its name, then the singer Robin Gibb, entries about 'Robin Hood' and so on. No entries are found on the first page about the birds known as robins. In fact there are no entries about the birds at all in the first 250 results.