I can's explain this...

[kosmiq]

this occurs because all XP versions shares the same .cab files (well most of them atleast). They are crosslinked all over the place, this means that when you extract it, it will get each cab file and put it with the rest of that windows xp files.
Hope you understood what I meant, I am not sure how it works but that is how it is done...

remove post if you feel it is necessary...

Edit: To clarify a bit,
Windows XP Pro and Windows XP Home uses almost the same cab-files, they simply use different files from it. Of course and Driver.cab will be the same so that will be on that can be linked to from another positition.
I also think that many of the cab-files might be some kind of dummies. So that those dummies works just like on some mini-images. Like BF2 mini-image from BleH, mount it and all files has the "right" size but are not usable.
So if Windows XP Home has the same driver.cab as Pro, one of them will simply use the one from another location.
Cr*p, this didn't get any better... Someone that can understand it and write it out so that someone can understand?