Why is there different mb in video cards? This may be s simple question to some of you but I don't understand the difference. I assume it has to with performance of the card, but how?

The more memory a video card has, reduces the need to source the physical memory of your motherboard.

Physical RAM is still pretty slow, restricted by the Front Side Bus speed of your motherboard, video memory has no such problem as it is on the same circuit board as the Graphical Processing Unit and can be accessed much quicker for increased performance.

Therefore, the more video memory a video card has, the higher an increase in performace you will notice.

At the moment anything over 128 Mb is unnecessary, and a waste, but that will change very soon with the likes of Doom 3 and Half-Life 2 which will make full use of 256 Mb cards for the first time.

Vid card memory used to be a function of resolution, until apps started using the vid card gpu to execute instructions. So today, vid card memory is a function of both data (resolution) and instructions. If you took any card on any system and tested it at 64MB, 128MB and 256MB, there would be no perceiveable difference. There would be a slight benchmark difference.

The reason 128mb and 256mb are popular is because vid card buyers are among the youngest and least rational.

Thank you guys for the answer. So I guess the 64 mb that I have is ok then. I wasn't sure of the difference. I'm not a very big gamer. I like the simple games like atari and such. I just wanted to make sure that what I had was enough for what I like to do. My husband likes "who wants to be a millionare" and it plays really good on my pc. I like the nvidia drivers better then the ati though. That's what I have now is the ati 9000 64mb. I think that I will go back to the gforce. The images on my screen look a little blurred to me and that's what brought that question to mind. Thanks again.