Only if you install the newest OS last will it autoconfigure the Dual Boot menu during install.
Install EasyBCD 2.0 beta
after doing quick registration to use beta. Add XP, accept offered boot files, let autocomplete, Save, Restart.
If this fails, post back a screenshot of your full Disk Mgmt drive map and listings, using Snipping Tool in Start Menu, attach file using paper clip in Reply Box.