Is my Graphics Card Getting support from my system?

I notice b4 i had 892 Mb of Ram when i put it in...Now i bought a Graphics card And despite it being 256mb 128bit and what not. I got my Full 1gb of when i look at system specs. im worried cause i See when their are shaded areas of various color on my screen is like a barcode of lines Shimmering what could this mean? i already reinstalled installed drivers but those lines still appear and i still have 1gb of ram... my Primary display adapter is set to AGP as my card is AGP also