Btw I ran my 5850 on 350 Chieftec PSU for about 3 months and it was running fine. Only when I overclocked my cpu AND gpu then it ocasionally shuts down. It was perfectly stable on stock speed.
My other parts are x3 Athlon II 720 at 3.2 Ghz, 4x1 GB ram, 3HDD, 1 DVD, Sound card, 5 case fans, lots of usb gadgets.
If your 350 power supply is quality you can manage with 5850, but it will be barely. I dont recommend it
I upgraded since to a 650 OCZ silver