Do you want to just install XP and not use Win7 or use them both together on the laptop? You need to look online for your laptop model number and see if it has XP drivers for it. You can install a virtual machine like VMWare to run XP in your Windows 7 environment also.
To get a dual boot of XP and Win 7, you are better off installing XP first, then installing Win 7, the Win 7 installation setup a boot menu to allow you to pick between the 2. It's possible to do it the other way, Win 7 then XP but it's harder.