What type of ram will fit an asrock g31m-s r2.0. motherboard

[glenny3868]

Hello,
can someone please help me, im going to build my own pc and have bought an asrock g31m-s r2.0 motherboard im wanting to put 4gb of ram in it but i dont know what type to use i know its ddr2 but i find it all very confusing when it says pc000000 and pc000000 i dont know what all the numbers mean and what difference it makes, can someone please help me and explain , thanks for any help, glen.

 

[ulysses35]

Dual Channel DDR2 memory technology
2 x DDR2 DIMM slots
Supports DDR2 800/667 non-ECC, un-buffered memory
Max. capacity of system memory: 8GB*