What do you mean the xp cd is older than the one your using right now?
You can re-install XP over the XP that's on their now and even though you'll lose all your programs, your data SHOULD still be there.
There are other ways people will say the've done it, it's always best to safely backup your data onto another storage medium before doing a fresh install. With the price of hard drives these days, do yourself a favor and buy a new one. Then you can use Windows XP file and settings transfer wizard to back up everything.