Was just surfing to se witch m-ITX cases are out there. Then i found the Casetronic Travla C138. it seems as a nice case. its small, supports 3,5" disks. "full size" graphics vie rieser adapter, So a hd 5670 might fin fine.
http://www.casetronic.com/product_d.php?id=0000000009
http://www.casetronic.com/product_d.php?id=0000000009