Hi Sommzy, welcome to NST.
Boot your W7 DVD, select "repair your computer" then "startup repair"
Do the whole of the above line 3 times
You should now be able to boot W7 unassisted by the DVD.
If it doesn't create a dual-boot menu automatically, install EasyBCD 2.0 latest build in W7, and use add/remove entries to add an entry for XP. Let it auto-configure when it offers. Don't change the drive letter it uses.