[Portable registry] tool???

I imagine a program that allows you to carry your registry entries with you and load them onto any windows OS/computer (that you have admin powers on). Optionally after the session you could update entries that were changed, and restore everything.

The most important things I could think of for my personal use would be...
- file type associations for portable software
- context menu entries for portable software
- adding whole software entries, for non-portable software

Well, does it exist? Is it feasible?
Even a tool that just allows mass changing of file type associations and context entries would be nice for me right now, it is very painful for me to manually do it.

PS - This is not directly related to windows 7, I guess it should support any windows OS.

The only thing that comes to mind, is using Acronis True Image 2010, so that Try And Decide could be enabled and then replacing the original registry files with the portable ones. Since it will restore the OS to the condition that is was before making changes, like installing apps, etc., I would think that it would be able to restore the entire original registry files also. Of course, I would save the originals, just in case it didn't work. Of course, TI 2010 would have to be installed on target machine...unless you had it on a U3 Flash Drive and ran it from there.