go buy a decent used pc, buy 2 5830s and sell old gfx-card(if not 5830), install poclbm and start mining in one of the decent pools, slush oder eligius or some else, thats it
why 5830 ? (or 5850) best MHash/$ ratio! you will have higher power bill, but more income too, so give a f*ck to the power bill
a properly overclocked 5830 will currently throw about 6$ a day at average power cost... 2x 5850 = 16,6$ each day = 500$ a month based on my experience, current btc/$, and
https://en.bitcoin.it/wiki/Mining_hardware_comparison jm2p Zeph