I have a ECS Geforce6100PM motherboard http://www.newegg.com/Product/Product.aspx?Item=N82E16813135074 and it come with 128mb Geforce onboard video card. I want to upgrade my video card but not sure which one to get. I want 256mb - 512mb if possible, which one would you recommend? and one of the specs said Share Memory: Maximum up to 256MB does that mean i can only go as high as 256mb video card?
It means that you can use up to 256MB of System RAM for your onboard video, effectively making it a 256 MB nVidia 6100 , which is a decent low end card. I cannot make a recommendation because you have provided any details on why you need a better card and what you want to use it for.