I recently started mining bitcoin through Slush's pool and am just wondering what MH/s rate I should be expecting and if there was anything I could do to speed it up.  I'm not a tech guru and have it set up on my Imac that has a 3.06 GHz Intel Core 2 Duo processor and a ATI Raedon HD 4850 512mb Graphics card.  The maximum rate I've been getting is about 40-41 MH/s.  Is this par for the course for the limited hardware I have and is there anything I can do to speed it up?  Thanks.