Internet/Program?

[Novice]

Hey, ya' all. I ain't got no problems ya' need to fix. I
was just wondering if anyone knows some cute little way to
make a certain program run only when you're connected to
the internet. Like some registry key that I could add
somewhere? (I'm trying to figure out ways to free up
system resources) Also, I'm on the hunt for a program that
can analyze my system and monitor fan speed & system
temperature. (Not necessarily in that order) I downloaded
one called "Speedfan" but it wasn't compatible with my
system. Anyone got any ideas?
Thanks!!