Duel channel is using two of the same sticks, so there's no way you are running in duel channel. I've never comparied the differences, but I'm quite sure you'd notice quite a difference.
Also, I can't remember for sure, but I'm pretty sure you need basically the identical stick of RAM. Just any 'ol 1G won't work, I don't think.
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Desktop * Athlon X2 4200 | 2G RAM | 160G HD | 7600GT
Laptop1 * C2D T5550 | 3G RAM | 120G HD | Intel x3100
Laptop2 * C2D T5250 | 2G RAM | 160G HD | Intel x3100
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