It is difficult to please them all.
Yahoo, Google and MSN each have different focus. If you can find out exactly what you can make a fortune in
SEO. I have several sites on the same subject....The indepth one does well on Google, the limited one with massive pictures does well on Yahoo
(number 2 on each respectively)
but the simple straight forward one with lots of content, but not much spread (it focuses mostly on one keyword) does well (5-6) on all the search engines. If you got Google you have 75% of all searches so you are in good shape