Re: 2 Modules better than 4?
The best course of action is to either use 4GB (more than enough in todays 64bit environment) at full speed or the 6G at a reduced speed. Difference between 800 and 1066 is merely benchmark numbers.
If it were me, I'd eBay the 2GB kit and bag myself a little spendin' cash. Trying to get unmatched modules (the two sets could have completely different IC's on them despite the same brand and model) to play ball is hit and miss. 99.9% of people will not tell the difference between4GB and 6GB.
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