Radeon 4770 issues

So I just brought a new video card Sapphire Radeon 4770, did a fresh full format before installing first with windows xp, specs are:

Intel Dual Core 2.0 Ghz
PSU 500W
Windows XP
Widescreen 1280x720
RAM 2GB DDR2
Sapphire Radeon 4770

I updated the card drivers, using catalyst 9.9 , I'm using it to play Aion, regardless if it's on very low on very high, framerate flows btw 12-17 FPS, funny enough at times jumps at 100 fps and keeps at 60-70 fps, I brought it to change a Geforce 8500 Nvidia Foxconn and I have to say it's not much of a improvement? am I missing something on the config? already sent it for RMA and this is a new replacement.