(Svend Rugaard @ Jul. 05 2008,17:08)
QUOTE
I would thinking of a structure like this
ROOT
I
I --- Vista
  I
  I --- VISTA Install Files and Folders like SOURCES etc
I --- XP
  I  Â
  I --- XP Install Files and Folders like I386 etc
I --- Misc
  I --- Everything else but this is not important.
The structure should be
Root
--I386 <-- this is the directory that winxp loader file (setupldr.bin) uses which is and can ONLY be located at the root of the CD, so if you change this name then you will have to hex edit the file setupldr.bin and rename the I386 to a directory name that you use and it must be 4 characters nothing more or less for example you store winxp files in XPEN then you will have to a search for all occurrences of 'I386' in setupldr.bin and replace it with XPEN. Once you have completed that then you will have to modify '\xpen\txtsetup.sif' and search for 'SetupSourcePath', and change [SetupSourcePath = "\"] which is the root to [SetupSourcePath = "\XPEN"] (not including []).
You get the idea.