In my truck I just ignore the light, but I know what the problem is there and it is an emission related thing that doesn't affect the performance of the engine.
With this car, I have had the light come on now for two different reasons. I've only had the car since October so this is getting to be a bit of an annoying thing to me. The first time it was a transmission component that was slipping. I'm still not sure the guy who fixed it didn't totally rip me off. He said it would be a six-hour repair job. I called him on Monday at 11:30 and he said he was just pulling it in to get started on it. At 1:30 he called me to tell me it was done...that's two hours not counting a lunch break. He still charged me the $350 he quoted for the six-hour job it was supposed to be. I just got the car back on Monday night, and this morning the light was back on. My immediate reaction was that it was going back to him, but the code reader says it is a different problem this time, related to the emissions system. I found a thread on the exact same code on here so have posted to that thread hoping to get some additional info. It sounds like it isn't anything to be too concerned about so I guess we can clear it out and see how soon it comes back on.
If the light is going to continue to pop on every week for something new, I'm trading it in and letting somebody else deal with it. I just wish I hadn't spent the money for top of the line Goodyear tires for it to keep me from getting stuck in the snow!