Now, since day one, I've not been a fan of dual-boots so that warps my answer to you.
My advice: backup all data dear to your heart.
Then make a true clean install using following tutorial: SSD / HDD : Optimize for Windows Reinstallation
some of the others do regularly use dual-boot and I'm sure they will point you in the best direction for dual-booting.
Once you start using Win 7, then you will never look back. In other words, XP will simply become a memory.