I myself have been sitting on a slightly old, but fairly up to speed rig; a good CPU (AMD Phenom 4X) but clearly the GPU is where it is on the mining scene, and the best I've got is an HD 4XXX series card (I forgot the specific model #). If I get such a rig setup w/ say, that custom linux distro for mining, could I get my system working well enough to get a bitcoin or a few every week? Or would I have to hunt down a stronger card?