We are fairly new to SEO, but that said, we have put in alot of work to create good content built around our targeted keywords. In a very short time, Google and Yahoo have indexed hundreds of our pages. Our page placement and rankings within our targeted key word searches is well within expectations on those sites. We are on pages 1-5 for the majority of our targeted keywords. MSN has crawled us a few times and after a few months we still have but one page indexed and to be honest I can't even find it using any keyword searches.
Since our efforts have yeilded expected results in the other major search engines, I would not even know where to begin and actually would be remiss to change anything that would negatively effect our placement in Yahoo or Google.
The only thing I can think of is lack of inbound links. We have a couple. Where should I start looking? Is there help or support available?