ok im new here and was reading ur post and its the closest i can get of what i trried and failed..... so here it goes... 1: if i put mce2004 cd 1 and start installing, when it asks for cd2 and i put cd 2 of mce2005 will it install mce2005 application? 2: this is intersting..... i have 1 cd of xp pro sp2 oem version and i have mce2004 2 cd aswell oem both non pirated. is there any way of using cdkey of anyof my xp pro oem or mce2004 in mce2005 , even after installation. i.e changing cdkey later for activation. what i want is use my oem cdkeys so i cant activate mce2005 online.