What's better: dual-channel memory mode or a bit more RAM?

[compdoc]

> Will A or B give me better performance?


One thing to try is memtest86+. Test both A and B configurations, and memtest 
will tell you how fast the bandwidth to the ram is. You probably won't see a 
lot of difference.

I've been reading that with quad cores, you want to run in unganged mode. 
(which turns off dual-channel mode) This allows the cpus to access the banks 
of ram independently. This is supposed to be faster.