The CD I made the ISO from was slipstreamed with SP2, so it may have been misnamed when making the slipstreamed CD. I wrote it wrong in the main post, it is really VX2PVOL_EN.iso, and that's what I used in the command prompt.
I read Microsoft Support's official article on making an unattend install, which used a floppy instead of the CD, so that was the only way I knew. I'll try making an ISO with the files.
I tried SysPrep just to see if it would work, but it did not.
In QEMU, you can feed any image in via the command-line. Since the IMG was not saving correctly (and giving errors in both QEMU and Explorer), I used an ISO.
I use QEMU because I need a free and fully portable VM, as the VM is going on a USB 3 flash drive.
Yes, I do mean this "Unattend Install Group"...
EDIT: I can't edit the ISO because PowerISO has a 300MB limit for saving and editing files unregistered, and it costs too much for me right now. I'll look for other programs (maybe ImgBurn?)