There is a cool new rhythm interface for your pc for the boss br series coming out in mid feb. It looks great and should make it very easy to lay down a good drum track quickly, and its going to be a free download. Check out the thread ->
http://microrecorders.org/community/rhythm-and-drums/boss-br-rhythm-editor/0 and the screenshot ->
http://www.roland.com/products/en/BR-900CD_Version_2/images/info_03R_L.jpg . I'm stoked because it will work with the br600 ?