In Windows search, I keep accumulating blue files like, $NtUnatalkb883939$.  What is the story on these? If safe, is there a way to delete them all and/or prevent their accumulation?

   They are your Windows updates.

I believe you are right about their being updates, but think they have been installed.  There are around fifty of the $NtUninstalk --------------$ folders and are much the same, mostly over one megabyte.  The common files are spunist.exe (windows service pack uninstall, spunist.inf (setup info.) and upds.dll (windows servicing setup API.  It seems that everytime I turn around, more are added.

   Our program, A1Click Ultra PC Cleaner (http://www.superwin.com/a1clean.htm) cleans out the ones that are older than 2 months old.

I heartily reccomend A1click Ultra PC Cleaner as about the best clean-up program I have ever used. I routinely use four other Registry cleaners but, after running them, A1click PC Cleaner found and removed over 5,800 entrys. My PC ran much faster and it has NEVER taken out anything I needed.