OK, this is just MY opinion but, I would rather have the Walmart one.

It is smaller, almost definitely much quieter, and draws less power. My main machine is an Athlon XP 2000+, so any machine in addition to that one would be used as a server. In a small apartment, the quieter the better since there is no basement to hide noisy machines in.

My point is that neither of the machines are fit for use as a workstation... only file server duty. So, for me, it is better to have something that is cheaper and quieter. That's just me though.