Yeah, the only benefit of doing this I could think of would be as a conversation peice. I mean, you may be able to get say, 500 KHashes/sec(and that's being extremely optimistic- the mining hardware page says only about 200 is to be expected), but still, that's unbelievably slow all things considered. But hey, I'm not going to stop you. It'd be entertaining in the sense of a 'screw it, we're doing this' sense.