ISAPI REWRITE code needed for beginner

Hi There

I have the following url

http://www.domain.com/products/index.php?category_id=$cat
and
http://www.domain.com/products/index.php?product_id=$prod

but for seo purposes would like these pages to be accessed by using the following url

http://www.domain.com/products/category_name
and
http://www.domain.com/products/category_name/product_name

I would like to have spaces replaced with hashes and for the product page would like to have the product name as well as the category name showing (is there a way to do a db query in order to get the category name)

Thanks in Advance