Do I need to worry about these temps?

Idle? Yes. Playing, nah.

Also, stock CPU cooler, I guess?

If you have such temperatures when idle, then you need to worry. If you are playing, then these are in the limit of normality.

I don't suppouse they are anything too bad. Probably could clean up some if needed and check the circulation...

They are pretty ok, considering you're playing a game.

Run away, it is gonna BLOW!!

Just kidding, the temps are good... Kind of.

You should look for a better Cooler. My Overcloked I5-2500K is running at 4.5GHz and my temps are better than yours.

I have never playied Dirt 3, so I dont know how much demanding it is, but your GPU temp is a little too high for my taste.

I use a GTX660TI (with should be on the same level of yours HD78**) with stock cooler (ohhh god, how it sucks) and a game must be REALLY HEAVY to make me hit ~60Cº. So far only Max Payne 3 and a heavilly modded Crysis 1 made me hit those temps.

Anyway, in the end of the year im getting a Accelero Xtreme, and my gpu will be cold forever.

Your temps are perfectly fine if that's a photo of that you took during the game!
40C For CPU and 59C for GPU during gaming is a very good temp.

A bit hotter than my build gets, but I have an aftermarket CPU cooler and my chassis is an airflow beast.
As others said, just get a can of compressed air, open up the side and clean everything out :)

Thanks for help and advice. I was planning on cleaning it out soon anyway so this gives me an excuse to hurry up. Also been looking at CPU fans.

I had a freind whose temps were getting between 60-70 degrees celcius. He wasn't too worried, until I converted it to fahrenheit....

If I remember right, that may have been idle.

Looks fine to me

No that's good temps. When playing games GPU's temprature averages at around 90 degrees celcius. It's because I overclocked my GPU, and it only has a heat sink and no fan. I've had it for around 3 months and only had a problem once, where my GPU had started burning up a little bit.

Do NOT use speedfan, it is really really really inaccurate. Use programs like "real temp" for the cpu and "GPU-Z" for the graphics card. Btw it all seems good!

there fine, my gtx470 bbq edition runs @ 75 on idle lol .. my amd 6 core however runs @ 18-22 on idle :P