I use WinBuilder to build PEs, (I used to use BartPE a lot in the past but WinBuilder is a lot easier), what type of PE depends on what I want it for.
LiveXP - I'm more familiar with it and it's good for small size ISO, (fit on a 180MB CD with a few utilities), and RAM requirements are lower.
VistaPE/Win7PE - If it's going to be used with esoteric hardware, (Vista/7 include storage drivers that will run on almost anything without trying to hack more in), and there's no RAM constraint.
I used to create multiboot PE based USB flash drives with:
1) WinBuilder - To create the PE environments, both LiveXP & VistaPE/7PE.
2) Various disk images - dban, ranish, supergrub, memtest, gag, ntpass, etc.
3) Linux Live - usually Puppy or DSL.
4) Parted Magic
5) Various DOS apps - mbrtool, etc.
6) Windows apps - ImgBurn, hardware info, etc.
7) Optional XP installer.
All bundled up together using
USB_Multiboot. Probably a bit over the top but it was fun just to get it working.
But I also did PE2/3 multiple boot USB HDD/flash, directly adding the various wim files by editing the bcd file with bcdedit to add them in, as per:
Integrating multiple version of Vista Six PE2 environments on the one flash drive.
H7PluginBuilder makes plugin building reasonably easy, minor editing required afterwards to tweak them but better than trying from scratch. It's 3 years old but will generate BartPE and WinBuilder plugins.
It's been about 10 months since I last played with making PEs but I still try to keep up with the latest methods - I'll probably swing to WinPE3 and update the various plugins I had.
Perhaps I should have said, "Make_PE3 is the simplest way to create a simple Live Win7 PE." Adding stuff to it will be a bit more involved, you're better off using WinBuilder and one of the Win7PE projects found
here, it will be easier to add stuff to.
Addendum: Just found this:
Windows Forensic Environment - a Windows PE designed for forensic analysis of the system, (ie. it won't write anything to the system thus possibly corrupting evidence). I think I'm going to have to pull out WinBuilder again to have a play
