I don't like the 6 x 1GB RAM in the 1st system. It really limits the upgradability there.
Realistically, all the systems are going to be limited, as far as upgrades go. The RAM sslots are filled with 1GB sticks. If you go with a single card setup, you likely won't have a SLI/xfire capable motherboard, and the PSU would likely barely support the single card you choose.
If you're going to buy from them, I would suggest spending to get the options you want/need, as you likely won't be able to do much to the system down the road.