Anyone still mining Bitcoin with a standard system is wasting their time and money, that ship sailed long ago. The smartest thing to do if you still want to mine is to jump on younger currencies like PPCoin or Terracoin if you don't think they're scams. But really, SHA-256 is a dead end, once ASICs are commonplace, all SHA-256 currencies will be out of the hands of regular people, the best bet is to jump on Scrypt based currencies like Litecoin, they are ASIC immune, and you can still make money with a decent rig. Mining though is limited anyway, it's probably better just to drop some Fiat on Litecoins/Bitcoins directly through an exchange and trade on the market, you're more liable to earn a profit that way.