650 Watts x 24 hours = 15,600 watts Used. 
Need to convert to Kilo = 15,600 / 1000 = 15.6kWh used
Electricity is .13 a kWh ..

so your bill will be:  $2.03 ($2.028) -- I rounded up

I used my quad core 2.6GHz cpu and I was getting 10mHash/s.  I dropped in a 6970 and I'm getting like 335mHash/s.  Big difference.

If the BTC comes down to like 5 to 6.. then I'd buy buy buy buy buy.  I'm sure the btc will go back up to 15 to 18. 

I'm new to this whole Bit Mining thing.  Perhaps I jumped in a little to late.  I made my first BTC the other day and sold it for like $18.xx and then MTGox got nailed.  Fun times.