If I already have this 2x256MB sticks of this RAM <A HREF="http://www.samsung.com/Products/Semiconductor/DRAM/RDRAM/RDRAMmodule/NormalRIMM/MR16R1628DF0/MR16R1628DF0.htm" target="_new">http://www.samsung.com/Products/Semiconductor/DRAM/RDRAM/RDRAMmodule/NormalRIMM/MR16R1628DF0/MR16R1628DF0.htm</A> in my mobo, can I add 2x256 sticks of this RAM <A HREF="http://www.ncix.com/products/index.php?sku=8249&vpn=CMXR256-1066" target="_new">http://www.ncix.com/products/index.php?sku=8249&vpn=CMXR256-1066</A> to it?