MS made good on not providing ISO downloads here: Microsoft Fixes Windows 7 Student Edition Upgrade Problems
You can unlock all versions in the ISO using this tool: http://lifehacker.com/5438005/eicfg-...windows-7-disc
However to recover the MBR into Windows 7 so you can start it without XP, you only need a Repair CD: System Repair Disc - Create
The procedure is to mark Windows 7 Active from XP disk management, or using DISKPART from the DVD Repair console or Repair CD: Partition - Mark as Active
Next power down to unplug XP HD, change its cable to or set Windows 7 HD as first HD to boot in BIOS setup (after DVD drive), Boot the DVD Repair console or Repair CD, click through to Recovery Tools list to run Startup Repair up to 3 separate times with reboots until Windows 7 starts.