How much and what type of ram would you suggest? How much wattage does your rig pull from the wall? and is the 7950 currently the best $/hashes or $/wattage?
Thanks for your help
(Going by eBay pricing)
Of the current gen, the 7950 is easily the best Price/Hash.
Of the current gen, the 7790 and 7990 both have a higher Hash/Watt (but MUCH less Price/Hash, so I wouldn't consider them)
Previous gens have some good stats, but also drawbacks. 5830, 5850, 6850, and 6950 are very cheap and produce decent hashrates, but not very power-efficient and may have compatibility issues with certain drivers.
tl;dr the 7950 is probably the best bet, being most balanced of the lot and should play well with current drivers.
EDIT: For RAM, I've had a couple rigs with 2 GB DDR2 that were fine, but it's generally advised to have 4 GB.