Thanks for the info ;]
Yesterday I ran the following script on my PI:
It took about two hours to complete, and while the temperature rose to more then 66 degress, test was successfull - no errors detected.
However, earlier that month - my Raspberry was acting weird - some software failed to run, apt-get update - was failing, and Raspbian was becoming unstable - I set system to automaticly check and repair any disk errors during boot, restarted raspberry, and that was it - it never came back up again.
I don't know why I was getting such a huge disk errors, that even apt-get was failing, my PI was running on turbo, and was used as a mini server and a proxy server...
I thought my power supply was not adequate, but since it passed stress test just fine I don't know anymore.