I have an imac g3 400MHz computer. I have 256 mb ram right now with two 128 sticks. Would a single 512 stick work? or... could i use one 512 stick and a 128 stick?! I'm looking at this stick, would it work? http://www.newegg.com/Product/Produ...36&cm_re=168_pin_sdram-_-20-178-236-_-Product thanks!