hide months with posts only from a certain category

I’m trying to modify the list of months in my sidebar to display only the months that have posts NOT in a certain category…. does that make sense? heh

I have 2 categories: A and B. I want category A to behave like normal entries, and for the most part so far, I was able to exclude the other category on my archive pages, etc. But the months in the sidebar (using wp_get_archives) are listing a few months that are essentially ’empty’- meaning they only have posts from Category B, not Category A. I’d like to not have those months listed there…. Is there an easy way to do this? Or should I start digging for a PHP solution? (query_posts or something?) hm..

Please help ?? thanks!