You might just end up wasting your money and your mobo wouldnt recognize the module cuz of the size. I have seen it happen although there may be an update for the bios on your mobo that would enable you to put the 512 module in. I updated my bios and I can now update to a P4 with Hyper Threading Tech. :D
check out your mobo site and find the latest bios. Or just go to best buy and purchase a 512 mod. and if it works order the much cheaper module from
newegg or whatever and return the module to Best Buy for your money back. If it dont work then....