For gaminng having 50% of the channels populated with the highest amount of ram possible with the lowest latencies will garner the best results. For AMD / DDR 2 this is typically 2 gig sticks in 2 channels (for dual channel) for a total of 4 gigs. Populating the other channels will increase latency. For the i7 procs that run tri-channel the sweet spot right now is 2 gig stix in 3 channels for 6 gigs total.
Now with that being said, this is for gaming. For ram intensive applications where windows keeps hitting the page file then there will be benefits for the quantity of ram over increased latency. These intensive applications include video editing, maybe some hi res photo editing and defintely virtual machines. This was confirmed with the guys at maximum PC as well as extreme tech.
So Hawkeye is definitely correct as is Kona. I would say that people doing virtualization, coding, testing, hi res video and photo editing are not your average home users