Will installing XP on a laptop that has Windows 7 hurt it in anyway?

Yes, performing a normal Windows XP install will wipe your Windows 7 install. You can configure a dual boot, but it can get a little complicated and it can be very tricky to get rid of one of the operating systems.

Can I ask why you want to install Windows XP on the laptop? I’m sure I can suggest an easier solution for you to deal with whatever issue you’re dealing with.