You can use your 4 GB of DDR3 with any current computer. You might lose out on a tiny amount of speed if you don't have DDR3 1600 because that's the currently dominant standard, but slower DDR3 (e.g. DDR3 1333) will still work fine.
-What is best in life? -To crush your enemies, see them driven before you, and to hear the lamentation of the women.