the second is optional.

for video cards, there's not much diff between manufacturers until they start deviating from the reference design or applying a factory overclock. most 8800gtx are identical except for a water cooled variant. i suggest you go with best price/game bundle.

as for motherboards, there's much more distinction. check out the enthusiasts sites like hardocp.com, hothardware.com, and anandtech.com for motherboard reviews to help you decide.