I just purchased a new MacBook 2.2 ghz SR. I also bought 4 gb of RAM from Transcend. I was hoping someone might know how to tell or test if its running in dual channel mode. I got 2 x 2 gb sticks that are 667 mhz. They are the same part number but Transcend doesn't sell them in "matched pairs" like Crucial and others do. Anyone got any ideas?