I am upgrading both copier and print controller memory for a Konica 7130 and IP-421. Do I need konica brand memory (MU-413 and MU-405) or can I use PC100 144PIN SDRAM 256mb from a laptop for the copier and 128 for the 421? Does the memory density matter like high density vs. low density. Any infomation is helpful been searching forums for days. Thanks.