I used to mine bitcoin, litecoin, and ethereum using AMD 7950's, 6950's and 5850's across multiple desktops with about 2-3 cards inside each.

Just wanted to say watch out for the electricity bill because they are in tiers. If you go over a certain level, they start charging like crazy.

+1 to Nanopool that's what I used for ETH.

Lastly, a lot of people say just buy the coin and don't waste on mining. I disagree to an extent. It's a good idea if you like to game and it's an investment that gets paid back eventually while being able to play whatever games your into. +The video cards still have great resale value because of the mining demand.