So far that computer has had no additional problems. I did use HiJackThis to make sure there were no additional startup files or registry entries that I missed. And I scanned it with Malwarebytes too with no additional findings.
One comment on the original xpsdg6420222.exe file. Symantec identifies it as a Bloodhound.SONAR.2 file which "indicates a running process with behavior similar to that of a Trojan horse that records keystrokes. It may represent a new, previously unidentified type of risk." Definitely a risk that I don't ever want to see again.
Thanks to all those who left comments and I hope what I've shown you was instructive and helpful. I certainly learned alot and my next post goes into an even more difficult, yet similar problem on yet another kids' computer.