How to reinstall XP on hand-me-down Inspiron 1100

I'm an old guy with chronic heath problems that make it difficult for me to sit up for very long.

I received a  and old  hand-me-down Dell Inspiron 1100 laptop from FreeCycle Seattle and I have a Dell XP re-installation CD that a guy from a BBS mailed to me.

The laptop currently has the previous owner's XP installation along with a ton of her software and files.

I'd like to delete everything and do a completely clean re-installation of XP so as to avoid inheriting  any problems in her registry (as well as any malware or other issues that may be tagging along for the ride).

I tried booting from the Dell re-installation CD, but got stopped cold by the screen that says:

 "You chose to install Windows XP on a partition that contains another operating system.  Installing Windows XP on this partition might cause the other operating system to function improperly"

But, I don't want to leave any trace of the existing operating system.

So do I need to first repartition and reformat the hard drive, and then boot from the Dell CD?

Somehow I got the idea that the Dell CD would do the partitioning and reformatting automatically.

I'd be grateful for some coaching on this project,

Will in Seattle

a.k.a. "Clueless"

 "You chose to install Windows XP on a partition that contains another
operating system.  Installing Windows XP on this partition might cuase the
other operationg system to function improperly"