Product keys & CD's

“ Hello,
I have a weird question, hope you don't mind.
I have some windows xp cd's without product keys, genuine of course, and
then I have some product keys without the win xp software cd's from
computers that have dead harddrives and did not have a cd come with them
because the recovery was on the harddrive itself on a hidden partition,
can't get the software due to warranty expiration.
home with home, oem with oem, pro with pro, etc.
Sooo, I would like to know if it's possible to put the disks and keys
together, should I even try or is it a waste of time.
Any input would be greatly appreciated.