I would get a new one, back up your saves and thank god that the console is still operational. Almost all 60GB, 20GB and most 40GB PS3s will fail, it'll just take them a little longer to die.
http://forum.beyond3d.com/showpost.php?p=1388522&postcount=137
I think the best way to get a feel for the console failure rate is at dev studios actually. The dev kits there are in use 24/7, 365 days a year so they effectively get accelerated wear and tear. Early 360's broke en masse, I remember an entire wall built with broken 360's when I worked with 2K way back, it was quite shocking to see that many all stacked like bricks waiting to be returned. But that failure rate dropped dramatically over time. PS3's broke rarely early on (the test kits that look like retail PS3's), but they have continued to break at a relatively steady rate to where given enough time eventually they all broke (the early models). As far as I could tell, all launch models of both machines are doomed to eventual failure, it just takes PS3's much longer before failure. I presume this has all been fixed now since anytime there were kit failures at the last place I was at they were usually older models.
I would suggest a slim, you'll be much better off long term for it.