ren %systemroot%\SoftwareDistribution sdold123
At this point I get an "Access denied" error message, although I'm using the command window as admin.
I ran into a similar problem with the "ren %systemroot%\System32\catroot2 cr2old123" command. It turned out that the bits service was being turned back on for some reason. When I retyped the "net stop bits" and quickly followed it with the "ren %systemroot%\System32\catroot2 cr2old123" command, it worked.