Should I re-install WinXP from my DELL CD even though it’s an older version

I’ve been having problems with my XP programs. Many are missing when I try and launch them. I thought about re-installing my XP using the original disc from DELL. But it tells me it is an older version than the one on my computer. This must be because of the windows upgrade from service pack 1 to sevice pack 3. I know I still have the only version of XP on this computer that came on it when I bought it new. Is there something I need to do to make this happen?