If you want hours per day, that's exactly it. Hours/Days. 1927/580 = Hours/Days = How many hours you play per day.
However, this doesn't account for the fact that you may not actually play EVERY day, so if you have a life and one day a week you don't play, your hours per day PLAYED would be a bit higher than that. If you want to know how your ratio of hours played vs. hours not playing (ie how many hours to you spend playing vs hour many you spend doing other things) just divide by 24, so that ratio is about 1:7, aka you spend one out of every seven hours playing video games, if you take out sleep it's probably closer to 1:4.
That also doesn't take into effect that if you're like me, xfire causes some issues with some games, and so you (I) shut it off sometimes for playing those, also xfire doesn't record EVERY game, there are a handful it doesn't know exist. Also, if your xfire is off for any reason (like you shut it off to play 1 game, but didn't turn it back on when you were done), these ratios will all be skewed towards less hours/day.
Trust me on the math, though, and if you have any questions ask again.