You were close... Try using WHERE forumid!=XX instead.

By the way, that will work ok for you now, but once your board starts to get bigger you will start to run into problems... I thought about using that on my site which has 300,000+ posts, but it took my homepage 30+ seconds to load. I should be able to split the polls query up into 2 separate queries though that will do the job much more efficiently, so when I do I'll post the code here for you.
Oh, and search engines shouldn't have a problem spidering the pages you added in your templates.