I want to add some RAM to my mom's older computer. She doesn't use it for much, but it needs more RAM to help speed it up I think. Planning on adding 2 GB (2 each of 1x1GB memory sticks). It's an older Dell desktop, a Dimension E521 with an Athlon 64 X2 3800+ 2.00 GHz processor. The invoice lists the memory type as "DDR2 SDRAM at 533 MHz". I can find this RAM at places like Newegg.com and Amazon.com for pretty cheap. Question I have is they list some of this RAM as "Non-ECC Non parity Unbuffered". How do I know if this will work or not, or if I need something different? Here's an example at Amazon.com. RAM @ Amazon Also, what's the max amount of RAM that Windows XP 32-bit can address/use?