if you mine BTC with a computer like that most likely you will earn just a few satoshis per day or less. Maybe mining a new alt-currency and waiting for it to grow in price if it had potential might be a good option IMO.
Read this post for why mining an altcoin instead of straight BTC is almost always a bad idea.
It might be true, yes, but he has a really old computer and he won't mine anything. If he has a good processor he can mine some alts with CPU, but you can't mine BTC with CPU so that's the problem..
