Newbie trying to update computer video card...?

Hello All!! Currently in my computer i have a 128mb geforce fx5600 ultra video card in my computer. I want to upgrade to hopefully a 512mb card. I am not 100% sure what i can put in my system... my motherboard is about 6+ years old. the blurb from the manual on my motherboard states.. "The AGP slot allows you to insert the AGP graphics card. AGP is an interface specification designed for the throughput demands of 3d graphics. It introduces a 66MHz, 32 bit channel for the graphics controller to directly access main memory. The main board supports 8x 1.5v AGP card. my motherboard is an MSI K7N2series with nvidia nforce2 chipset. and amd athlon xp 2100 processor.. any suggestions as to whether a 512 mb card will work with this motherboard? I have no clue :) I am planning on sticking with geForce since i have had no issues whatsoever... any suggestions?