Views Block on a Node with Taxonomy Argument

Hi,

I'm struggling to get a block view to work on my site. Basically I want a view of node titles to appear in my sidebar. The block will appear on nodes that are of a content type called "articles". These "articles" nodes are classified under taxonomies, and what I want to happen is for the block view to only show node titles of other nodes that have the same taxonomy as the node being viewed. However I can't seem to get the view to work the way I want.

Hopefully I've explained clearly enough! If anyone could point out how I should setup the argument for the view that would be great.

Thanks for any help.