I am shopping for 6 sata drives for my NAS. I dont need a lot of storage so my focus is on performance.

The NAS has SATA II controllers.

That said, I used to look for 5400rpm vs 7200 rpm. However, that doesn't seem to be the whole story.

Here is what I think I need to compare:
1) Host to/from drive (sustained) performance in MB/s
2) Heads/disk count

Here are the two I am comparing:
WD http://www.wdc.com/wdproducts/librar...879-701338.pdf
Seagate http://www.seagate.com/staticfiles/s...100649225c.pdf

I think the seagate is going to be the better of the two. Any thoughts?