I want to buy a 512 MB or 1GB graphics card. May you help me to select?

It's DDR2-800 MHz. We need details. What is it going to be used for? Gaming, video editing..?

u should buy a ATI radeon HD 5830 card. its got directx 11 support, opengl 3.2, shader model 5, 3D display support, hdmi support. its got an engine clock speed of 800 MHz and a memory clock speed of 1 GHz.plus its not that expensive, its around 150 dollars.

First of all, it is not a matter of graphics memory size because what is more important is the speed of the memory that the graphics card. Example, a 512 mb DDR 3 graphics card will probably outperform a graphics card with 1 gb ram. I suggest that if you want a cheap but decent graphics card that can play new games at a decent level, opt for atleast a graphics card with ddr 3 memory but ddr 5 or more would be awesome. Also, remember getting optimum performance from a pc does not just rely on one hardware but as a whole, so it's about the combination. If you have already a decent cpu, then only 1gb ram, don't waste your money on a very expensive card. It's better to balance things out, like add more ram and buy a decent card but not to high end.