oh. i saw a website that compares video card. and i can see 9600 and 4670 beats the other 3. but the 9600 requires x2 energy consumption. so what will i do if that's the case? need a higher AVR? higher power supply? will it cost more electric bill? if the 9600 will give me a problem then i think i'll go with 4670.. but is it ok if my built in video card of my mobo is geforce?
Well, the thing with graphics cards and power supplies is that you have to make sure your power supply is a) good and b) has the right connections. Most the time b) isn't an issue if a) is met, because you can get a variety of adapter cables. The 9600 gt requires a 6 pin power connector and at least a 400W power supply AFAIK, but more importantly you have to make sure your power supply has at least 20A on the 12V rail (if you don't understand that don't worry I'll explain), but to be safe and depending on your system config you want 25-30A just to be safe.
If you're not sure about all that, the 4670 is great from the point of view that you just plug it in and go. No funny cabling, not too much worrying about your power supply, just plug and play.
i really appreciates all the replies. i think i'll just go with the 4670. but are ATI products reliable? i'm an IT student but i'm not that good in hardwares. so i think i'll have a problem if i use the 9600. also, how will i know if my mobo can support DDR3 video cards?
ATI products are great, you have nothing to worry about. If your motherboard supports PCI-Express, it will support any PCI-E card you put in it. It doesn't matter if the card runs with DDR2, 3, 4, or 5 VRAM. That's the only thing, make sure your mobo isn't AGP and you're good to go!