I just received an external monitor( Dell 2007 wfp) i bought from ebay. I want to use it as a 2nd monitor with my iMac. I have the Power cable and the DVI cable. I know i have to buy the miniDVI to DVI adapter, but then what ? I heard that i had to buy an extension cuz the adapter is only 6" long(if yes, which one do I have to buy ?). I plug the adapter to both monitor, then i plug the power cable and that's all? Thanks for the info.