I've just recently upgraded my graphics card on my computer from junk..to a nvidia e-geforce 7600 and with this came a lovely error message saying that the graphics card was not recieving sufficent power. I did the obvious and went back to futureshop and bought a new 400w psu and installed it. and my problem of games freezing while i play still persists. ive cleaned all my fans attached a molex power connector to my graphics card to my psu and i am out of ideas......

please help!

Usually either incompetent Power Supply, memory that is too slow, such as Value Ram, too much heat that the heat sink cannot efficiently draw away, heat elsewhere, or an inadequate video graphics card. 400 watts, in a less than stellar power supply model, may not have been enough. This is often where the quality of a power supply shows itself.

do you suggest buying a more powerfull psu or should i buy some more ram?

I don't know what brand of psu you are using, but I believe raybay is saying that you need a better quality power supply. Then the rams next may be.

Sort of depends on the memory... DDR is starting to become more expensive. DDR2 and DDR3 are becoming astonishingly inexpensive.
But the device that makes the most difference in your computer, next to the motherboarde, is the power supply. A quality power supply engineered to provide constant amperage and wattage underload on all of the rails, while running quietly is a prize to behold... It makes all the difference in operation and long life of everything in your computer.

the brand of my psu is a dynex. not sure if thats good or bad.

It is ok, but it does not have the steady output that is needed on a top graphics card... you may occasionally get dips and blanks after a lot of use as the heat builds up.