virtualbox.org

What upgrade from what old system? I thought we were doing a new install of Windows 8.1 from disc into a new vm. If this disc is not the Windows 8.1 installation media, what is it?

Right now I have an XP system and I want to upgrade to an 8.1. It was never my intention to do a fresh install. It's a Win8.1 disc, which offers to do an upgrade, rather than a fresh install, but it says that to do so, I don't boot from the disc, but start XP and begin the upgrade from there. When I try to run the setup.exe from in XP is when it hits the fan.

As long as you have changed the template as discussed earlier, any further questions are really Windows questions. Any errors you see should be Windows errors, not VirtualBox ones. Check out the XP to Windows 8.1 guide below. It might be worth running the upgrade assistant.

http://windows.microsoft.com/en-au/wind ... p-tutorial.

The difference between doing this on a physical machine and a virtual one are very slight.

I can't actually duplicate what you are trying to do. I do have an XP guest but I do not have a 32-bit Win 8.1 disc or ISO. I only have 64-bit versions, which of course won't run in 32-bit XP.

Oh! That link you provided says that you can't upgrade to Win8.1--you have to do a clean install. But it tries to do an upgrade. I'm not sure what to think now.
I guess I can go to a Windows forum, but as soon as they find out I'm going this on a virtual machine, I expect they'll pass the buck back here.

I doubt you need to visit a Windows forum. I think you can take it as gospel that you can't upgrade from XP to Windows 8.1. In fact I would consider it common knowledge: you can't even upgrade XP to Win7. That too requires a reinstall. Probably the directory structure is just too different.