yeah, models I listed above mostly sold out everywhere
5770 will be gone next soon
- mining is a reward system for dedicating your processing power to keep bitcoin network secure. when you mine you are including new transactions and some random nonce - hash it up and result is compared to a number relative to difficulty and once its lower - you have found a block for which you reward yourself with 50 bitcoins and everyone on the network will validate it, and if there were any transactions that you encoded with fees attached you collect them as a nice bonus. that's it in a nutshell.
bitcoins use ssl encryption, sha-256 which in today's word impossible to break, it uses p2p networking same one torrents use and i think there was another important piece of technology i may be missing here
more
https://en.bitcoin.it/wiki/Category:Mining