Ok i reinstalled the windows XP on my pc while the card was in there and it worked fine but then after about 5 mins the screen went blank and into stand by mode so im thinking that i dont have enough power
Could potentially be that, but I'd be surprised, the 9550s don't draw that much power. How hot is the card getting?
It's a driver problem, the same thing happen to me with my ati-x1650, it wouldn't recognize the latest xp drivers, I tried vista drivers and that didn't fix it. I had to use older xp drivers to finally get it to work. It's trial and error to find the right one, you might also try the omega ati drivers.