23 MH/s? If I were you, I'd stop immediately since you're wasting money instead of making any. You're already at the bottom line with that speed. And things will get really ugly, when difficulty increases, block reward is halfed, ASICs hit the field...
My GTX 570 is giving me 160 MH/s and I already feel kinda bad about it. Wouldn't mine with it all if the box it is mounted in wasn't running 24/7 no matter what, so I kinda don't mind the little extra in power costs.
TL;DR: You'll never mine a block.
~drekk~
