i want to buy a graphical card good for pcsx2 as i think i should buy NVIDIA OR ATI HELP me chooseing ............
If you're getting a video card especially with PCSX2 in mind, Nvidia are the recommended card since Gabest (the main graphic plugin programmer) only has Nvidia so he optimizes for them. That said, you really can't go wrong with a modern ATi or Nvidia card.
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What he said. nVidia just rocks
Whatever you will buy a card, get 128bit and directx.10 support at least.
9800 GTX
Cheap, DX10 capable, will play just about any PC game on the market at full settings just fine, and will handle all your PCSX2 needs pretty easily.