Just went on a journey! Getting XP to upgrade was major pain, but it was all server config issues, not the fault of XP. I've got a story to tell...
Here is what happened:
We had the problem described above on the client site. TSS was certain it was a XP/QT problem and not their issue. So I balled it up and brought it down to my local machine. Got it running fine on Windows, but the upgrade script on my local Windows machine gave up pretty quickly without having access to tar.
So I loaded it on my box hosted at Hard Hat, and tried again in this Linux environment. Nope, no luck, missing the mcrypt Extension, and it would not run. So on a whim I popped it up on another TSS hosted virtual machine, this thing doesn't even have SSL support so I had no way to access the XP admin panel. I didn't let that stop me from trying the upgrade script though! It failed.
I got this error:
sh: patch: command not found
At least it was different! I contacted TSS and they quickly came back with:
"We have adjusted a setting here on our end to allow access to this function. Can you please try this again and let us know if you have problems?"
And I ran the script again, this time no Apache error or missing extensions errors, but database problems. The database had gotten corrupted during all my previous failed attempts. Deleted everything, grabbed a fresh copy of the DB and files from the client's server. Upload, Import, run the script, and Bam! We are in business. Packed that up, loaded everything back on the client site, opened up the admin panel, logged in, and there she was, working perfectly running 2.1.1
Thanks Alex!
Edit: I have now discovered with TSS help that the original issue was just operating in a jailed shell rather than as root. Feeling stupid.