Well, according to your information then, Athlon X2 5000 will run on the ASRock N68C-S UCC with DDR2 memory but if you want to run DDR3, you need the AM3 CPU... check this page:
http://www.asrock.com/mb/overview.asp?Model=N68C-S%20UCC&cat=Specifications
For the memory specifications it has these warnings:
*DDR3 and DDR2 are supported separately.
**DDR3 memory is only supported by installing AM3 cpu.
***Due to the operating system limitation, the actual memory size may be less than 4GB for the reservation for system usage under Windows® 32-bit OS. For Windows® 64-bit OS with 64-bit CPU, there is no such limitation.
****Support with AM3 / AM2+ CPU.
Sorry mate, you are out of luck on DDR3 or DDR2-1066 with that CPU. Can only use DDR2-800 or less.