I don't know which miner you are using, but I am using guiminer.  There is a spot that says device.  Before I updated my ATI driver only the cpu was listed.  At first I thought 4 Mh/s was good, (maybe for the cpu it still is).  Make sure you have it updated.  Because 2Mh/s is really low.  Don't expect to get anything with that.  Without overclocking my ATI 5770 I get 150-165 Mh/s.