How does MSN rank Web sites?

I have several sites ranked 1st page MSN. Especially this is the case for a '2 keywords' phrase!

I found it much more hard to get a high position for a 'single keyword'!

So I thought that maybe single keywords searches get more traffic & therefore has much more competition and sites that are ranked higher then me must have much more back links!!

Unfortunately, I saw that this is not always the case: I saw site ranked top-3 (= single keyword) with much less back links then mine, but my site is only to be found back on the 3rd page!

Maybe you say that the other high ranked site has better content, more often mention particular keyword, etc.

But how do you explain that I am ranked for several sites top-5 1st page ('2 keywords' phrase) if my content is less good?

I hope someone has an explanation for above mentioned OR can tell me where MSN crawler 'particularly' look at from own experience compared to Yahoo or Google?

Many thanks in advance for your help!

Check out Community Questions to the MSN Web Search Team
@ http://www.seomoz.org/articles/community-questions-to-msn-search.php

30 Questions submitted by the SEO community are responded to in this in-depth interview. Sections include technology, code, spam, recommendations and future offerings.

I hope that will help you...