here's my critique.

Economy Mining Rig
AMD Athlon II X2 250 @ 3.0GHz AM3 Processor (wtf? get a semperon or something)
2GB RAM (overkill. use linuxcoin)
1x ATI Radeon HD5770 GPU  (why would you even use that card for mining? even as an "economy rig". i would expect a 5830)
650W Power Supply (overkill. a good 450W would probably work)
500GB SATA HD (wow, can't you get something cheaper? like a usb flash drive with linuxcoin?)
DVD-RW (they should revoke your rig building license)

it seems like you're building gaming computers, not mining rigs. read up on how to build one over here: https://forum.bitcoin.org/index.php?topic=16076.0.