I'm planning to reformat my PC using winxp home edition,then I set the cdrom as my primary bootthen suddenly it say's "CANNOT BOOTH ERROR CODE : 4" does this mean that my winxp is not a bootable version?
No, it means there is something wrong with the disc IMO. All WinXP discs are bootable (I think). Try another bootable disc (whatever) and isolate the problem.