Ps3 + heat gun + thermal grease + power supply replacement to a APS-231 = Win
Same happened to my 60gb and here's what I found:
What has killed most of the old models is the power supply unit. They run extremely hot and will get as hot a iron for clothing. I've actually burned my hands on one once after it running for five minutes on dead cold start up. Also all the early models I've seen had little to no thermal grease on the processors. Plus the thermal grease was cheap and poor quality. This is why they die. I wouldn't buy a service to reflow it if you have a friend who can use a heat gun effectively.
Since I have had no problems with my ps3.
Also I'm against the slim idea, but that's just me.