First Time Builder - Need Temperature Advice

I recently bought and assembled a budget gaming/do-whatever-I-want rig (first time builder) and I would like to know if the temperature I am getting are acceptable.

Right now I'm running HWmonitor with Prime95 since someone said "just run that and watch" and given that people say temperatures for a GPU shouldn't go about 90c and CPU's shouldn't ever go above 70c I was interested in knowing if the numbers I'm getting are even considered 'good'.

On the Prime95 I chose the default balanced test so its just doing whatever the hell it does for the past 3 hours.

With the work load that was given my CPU temp is holding at 58c and has never gone about 59c
My GPU is holding at 45c and hasn't gove above 47c

My build:

CPU: AMD Athlon xII 260 3.5ghz (did an auto overclock that my motherboard will do on its own up from 3.2)
MOBO: ASUS M488T-V Evo ATX
GPU: ATI 4670 HD
RAM: Wintec DDR3 1333
HDD: WD 640g 7200rpm
PSU: Antec 500watt
CASE: Antec 900 2 gaming case

Are these temperature alright? Or should I replace the heat sink that came with with my processor since it was pretty small.

Any feedback would be appreciated.