Are you questioning the results of the virus scan? They appear real to me and IMHO you should take steps to clean up your machine. Get something like Hiren's Boot CD, which has a number of virus scanners and run two or three different anti-virus scans to verify results. "Guilty until proven innocent" is how I treat any results on my OS.
My advice would be to scan with a notable antivirus and antimalware program, I used HerdProtect when it first came out also and it gave me a bunch of false positives. I bet if you scanned with Malwarebytes or Emsisoft Antimalware your results would be completely different, ALTHOUGH I will say that even Eset Smart Security or Nod32 will pick up Trend Micro's Housecall as a positive and like you said Nirsoft always takes a hit it really does not matter what you scan it with. I usually put Nirsoft in the excluded from scanning category of my antivirus / antimalware scanners.