[SOLVED] Hide certain categories from main page?

I'd like to be able to exclude posts of a certain category from being displayed on the main page.

I'm trying to find a way to do this with plugins, to no avail (there are many options, but none so far I can find that work with Wordpress 2.9).

I use Atahualpa (old version - 3.2 - but am willing to upgrade if necessary) and was hoping there was an "easy" way to do it. I see it can exclude categories from showing on the category list... but is there any way to have it exclude all posts of a given category from the main page?

thanks!