If you're planning on doing mining to pay off the costs of your whole rig, then personally I'd rather just get a job. Mining is just going to wear out and degrade your computer faster. Though it completely depends on what coin your planning on mining. Personally though? I'd rather do something else to make back the money than to do mining.
I have to agree. You'd end up having to replace your graphics card before you have it paid off I think. Also, at least where I live, the electricity is more than I would get mining.