If the disc say for "reinstallation of windows xp" or something
similar it IS a windows xp oem cd (very likely what you have).
I do not believe Dell supplies a "restore cd" but
they do now supply a restore "partition".
The restore partion is accessed by pressing shift F11 (or something
like that) and not accessed from a cd.
You can easily tell if it is an xp cd by changing your boot sequence in
the bios to cd and then booting from the cd. You will
know right away if it is an xp cd (it will get message on the
screen to "press any key to boot from cd").
Hope this helps.
Dave