CPU Overheating?

I have a celeron 800 and a asus cuv266 and asus probe says that my motherboard is at about 30-35 degrees celcius and my cpu temp sits around 43-45 degrees c. both at idle. After i quit a game or something it says that my cpu is at about 57 degrees or so but then quikly drops. Are these temperatures normal? The graphics get messed up when im gaming and i need to know if my card is messed or my cpu is overheating. (asus geforce4 mx440. just got it, motherboard too. eitherway im getting a new one anyway, don't like it too much) I only have one fan, the one that came with the computer and it runs at about 4400 rpm. is there a way to make it faster? Could that be the problem? I don't know much about overclocking or anything like that so someone please help me.
By the way, i had the store install the mobo for me, wasn't me)