Why does Google hate me?

[annc]

For some reason, the Google bots don't seem to like the taste or smell or whatever of my main web site. I've got a robots.txt file, the pages validate, there's plenty of text on the home page. The MSN bots seem to think it's fine, although I don't yet see them in the vBulletin message board I created the other day. They certainly visited the old phpBB board fairly frequently.

But the Google bots just seem to poke their heads in several times a week without grabbing any content, and my message board stuff rarely shows up (even before the move to vBulletin, which I'm hoping will increase my Google exposure dramatically).

Any suggestions as to how I can optimise this site will be gratefully received. It's getting plenty of word-of-mouth promotion locally, and the message board is quite lively. I'd just like to draw from a wider audience.