*Can two different HDD'S be run at the same time*
*is the cabling/connections the same?*
No - SATA connections are quite different to IDE. Both the power connector and data cable are different. Does your motherboard have SATA connections?
Also - you can quite simply add another IDE drive if you currently only have one.
Also you can add an external drive via USB (USB2 is far preferable) or by FireWire if you have it.