Query Question

[Mysql List]

Hi,
Can any of you query experts tell me if this is possible in a query?
I have 3 tables, categories, products, groups.
Groups table consists of categoryid and productid, it just keeps track of which 
categories have which products.

I need a query(if possible) that would basically say:

Select all products that do not have an entry in groups with the corresponding 
categoryid of 1000 (example id)

Basically, I bring up the category on a page, with all of the products that are 
grouped with it, and I want to select all the other products that are not already 
there.

Category                    Products                    Groups
-------------                    -------------                    ---------------------
ID                                ID                            CID     |    PID
-------------                    -------------                    ---------------------
1000                            1                               1000    1
                                   2                               1000    2
                                   3                                                   
 
                                   4

Query would return products 3 & 4 because 1 & 2 are already grouped with Category 1000

         

Make sense?

Chris