PowerPro saves its settings in its own folder.
It doesn't modify the registry unless you tell it to.
I make these 2 statements from my personal experience; it doesn't mean they're the absolute truth!
Examples of some USB-friendly features:
1. Clipboard items and Notes are saved in the "clip" and "Notes" subfolders (they store the information un-encrypted, so be careful)
2. Snippets (predefined blocks of text that you use often and don't want to type over and over) are stored in "pproconf.pcf" file
3. Various commands like window control, system control, screen-saver, desktop control, schedulers, empty recycle bin, open/close cd tray, calendar etc., etc., etc.
4. Now for the most important part: launching programs from menus or hotkeys.
There are a few different ways to deal with this. A more complex but efficient method is by using ".runit" script.
I use a simpler way with "do" command, but the applications launched need to be in a subfolder of PowerPro.
There are so many things to talk about PowerPro....an entire day would not be enough!
I didn't say anything about the custom context menu, tray menu, taskbar menu. I don't use these features on USB but I think it's doable. Many features need admin rights, though.
There are much more features (like using .ARB script - Launchy like launcher); ask if you need something specific. I'll try to find an answer for you.