I'm not very sure this is in the right forum but anyway:

is there a way to install Windows XP with the Vista Setup?

So I mean edit the INSTALL.WIM so it extracts (and applies the settings) to
the Windows XP files?

Greetings from a new and excited member,

Caelestis.

first off get BDD2007 and the Windows WAIK you can do this quite easy once you have read the docs.
:-)

you can even put it all on a USB stick and install from it depending how big your image is.

Wow great! Thanks! But an someone put up an easy guide or something?
I would really appreciate it!

For once, the help docs that come with PE2.0 are really good to get the basics going.
Read the CHM that comes with BDD2007, it will get you going.