What MOBO do u have ? Just make sure that the MOBO has the necessary BIOS to recognize the dual cores. U should not have any problems fitting the X2 in the rig and get it going but if the BIOS does not support dual cores, then only one core would be seen by the OS. Install the X2, update the BIOS and u should be fine. Also do not install the IDE drivers from the Unified Drivers. NF IDE drivers cause lotsa troubles.