yes this the same experience I had my dual boot setup with windows 8 lets me access all my files on the XP drive I had to get permissions to do it but it let me. I had two instances were I was not able to retrieve the files from a XP SP3 installation one were the mobo in my old machine failed (even though later I found it was the AGP slot on that mobo that went bad could have retrieved files using a PCI GFX card) and on my friends laptop that would not reinstall XP. When I tried to get files off the HDs on another machine XP would say "you are not the original owner" and denies access to certain folders like my documents, program files and the windows folder WIN8 does pretty much the same thing it tries to get permissions but says you are not original owner even tried Ubuntu. But all this may be irrelevant to the thread as a high end 2004 build probably doesn't need SP3

I've never used Win8 so I dunno about that one.
I've never run into such a problem with XP-SP3 and I imagine if that problem does exist it isn't related to the SP level.
I have seen various "you don't have permissions" messages like you mentioned via LAN, but all getting around that entails is logging into the OS installation.
The HP laptop may have had some security nonsense going on via a hidden partition and/or a security chip.
- Anyway, I think the problems you had were XP related but not exclusive to SP3. You just happened to be using SP3.

I have several Panasonic Toughbook laptops were the factory restore CD/DVDs are actually HDD images of the original installation.
As in a clone, not an installer. Thus I can't slipstream any updates into the restore media.
Those load up XP w/SP2 and trying to install SP3 later crashes them for some reason.
I just use them with SP2 and I haven't had any problems because of it.
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