Alright, on this machine everything was working perfectly until I converted to the RunOnceEx method, then the PC will hang at the Windows XP load screen. The progress bar just stops. On any other computer the install goes perfectly. The only special thing about this one is it's SATA hard drive, but that wasn't a problem before I converted to RunOnceEx. I've updated the driver folder with the latest Dell drivers I could find for the model, still no help. I've rebuilt the disk from scratch. I even removed SetupCopyOEMInf.exe in case that was causing problems, still no help. Any ideas?

R u sure that Dell didnt change the device driver ID for the SATA controller driver?

Then u have to add the corresponding entries to the TXTSETUP.SIF. Like u I have GX620 as a standard comp model @ work, and I just needed to change / add the device driver ID to my TXTSETUP.SIF file... then again, the installation should not halt that late in the installation, rather really early, as soon as it wants to write to the disc.

Hope u get lucky.

I'm getting more and more certain that it's not a driver issue at all. I can boot into safe mode (but not with networking) and the only driver having any issues is the NIC driver, that asks for a .sys file, which I point to, and then everything's fine with that one. As for the SATA driver, I don't think that could be a problem if the entire installation goes through before it hangs.

Okay, never mind, it WAS a driver issue, but not the kind I thought it was. Turns out that on this particular model, the Drivers from CD trick (with presetup.cmd) will not work, as SetDevicePath.exe apparently writes the wrong kind of path. I went back to the winnt.sif method, manually writing in the device paths, and everything installed just fine and dandy. I guess let this be documentation that these particular drivers have issues with the presetup.cmd method.