I have few examples :
I have created a Live USB with Windows ADK (Windows PE 4, a Live "Windows 8") : with that program that boot (even with EFI, or with secure boot EFI) I can run diagnostics for PC with problems, change files, registry keys, test hard disk, RAM, Ghost, install Windows, download programs or drivers on internet if needed, etc...
In fact, it's a home made "all in one" tool.
I also use AIDA64 into my "Live 8" with a x86 system, but many new computers can't boot with legacy bios mode ; so I use more and more a x64 Windows PE, but AIDA64 can't run on it.
I had the same problem with Firefox that is compiled only for 32 bit systems, but I'm lucky, an open source project compile it into 64 bit : Waterfox.