After reading for a while the drivers DDK I couldn't see anything referring to executing files so I think that it could be possible to merge all the INF files of all the drivers into a single one, and creating cabs for each driver to save space (because if the INF files can't launch other applications then they won't have problems with the files in the cabs).

This should speed up enormously the drivers install from the CD because reading all the INF files from the CD is SLOOOOOOOOOOW and also it's slow to extract all the 7zip files while xp installs.

What do you think?

In the meanwhile i'll give the DDK another look to make sure that applications can't be run from the INF files: even if they can be run the drivers could be left unpacked solving all the problems. Or ir could be possible to launch an application to unpack just a single driver before installing, or things like that. I'll keep you informed.