Ghacks posted a tutorial about crating an Integrated x86/x64 Windows 7 Install DVD

One of the biggest problems with Windows, every version in fact is that there is a different installation DVD for each version. Whether that’s Starter, Home Basic, Home Premium, Professional or Ultimate that’s nine different discs you need as each of these comes with a separate disc for the 32-bit (x86) and 64-bit (x64) versions of the operating system.

  How to Create an Integrated x86/x64 Windows 7 Install DVD