open up the side of your case and read what it says. Look for the make, watts and the amps on the 12v rail. If you can't find the amps, dont wry about it, if u can find the make and watts i can figure out how many amps it has anyways.
PSU is on the top left hand corner just incase you don't know lol. Also if you had a previous card in there, be sure to whipe out its drivers completely then freshly install the 9800 pro with new drivers for it.
P4 2.8E @ 3.5Ghz(24/7),3.72Ghz (benchmarking) 1:1
Abit IC7 Max 3
2 X 512mb OCZ PC 3700 dual channel Performance series ram
EVGA 6800GT @ 440mhz/1.2Ghz(24/7), 451/1.23Ghz (max benchable)
2X80 gig SATA RAID 0 drives
SB Audigy 2 24bit
Black X-Blade Gaming Case
Enermax 460 watt PSU
CPU Cooled By: Thermalright Xp 90 + 92 mm panaflo fan
GPU Cooled By: Arctic Cooling Nv Silencer 5 Rev. 2