Airport Connection Issue

I bought my MacBook in 2006. After the first two years it has an intermittent problem connecting to wireless network. I teach part-time, mostly it was an issue at various homes in which I was teaching. I never used to have problems at my home until a few years ago. First I was told by Apple Genius heat sensor issue (they fixed, no improvement), now it's supposedly an Airport issue now that it's no longer under contract. So I've been told to go to a repair store since Apple no longer supports my "vintage" model. Friday it lost the connection after having it on most of the day upgrading the system, etc. It wouldn't connect even after shutdown - same thing today while streaming a video when the fan came on. Could it be a problem related to heat, long duration of use? So I've been reading all the posts on here, about how there's a problem with wireless after 10.5.2 update, etc. I'm at work without the MacBook, so don't have the latest update to note, but it's whatever the latest one is right now but for Snow Leopard operating system.

Anyone have any advice before I take it to a repair shop?

Thanks.