I have just put some more ram in my girl friends computer but it is not showing up in system properties. is there any thing i have to do to get it to recognise the ram? the computer is a old hp pavillion 533a with windows xp it has pc2100 ddr sdram 256 mb in it at the moment and i have installed another 256 mb stick but it is ddr pc3200 400mhz but says on it that its backward compatable with 266 and 333 mhz. is it that the ram is wrond type or that the mother board cannot handle any more ram?? sorry about the spelling any help would be great.