I have a Compaq Presario with an AMD 2600, W-XP, 80G and 20G hard drive, 48x24x48-16 dvd-cd-wr, 48x24x48 cd-wr,256 DDR 2100 ram. I have checked several places on the price of more ram. I want to add a 512 stick. Any suggestions for a good price on it? For one place with a price of $89 for a 512 stick.