[magus]

Oh, You
good title

 
Ready followers?   ORNOT
Mouse catcher   OWL
Mart opening   WAL
Ones needing a lift   SKIERS
Joint just above ground   ANKLE
Chilling spots   SETTEES [chilling is slang for relaxing, but it took me awhile to get it]
Theme: U substituted for second O of a double
Parasite extermination overkill?   LOUSECANNON
Lead actor in a war movie, at times?  SHOUTINGSTAR
Do-gooders long term goal?   ROUTOFALLEVIL
Cause for repeated whistle-blowing?   CHAINOFFOULS
Plus some interesting and varied entries --- and all 26 letters used.

 
Some Windows systems   NTS [don’t know what that means, but I may have one]
Nag   HENPECK [henpeck denotes consistent nagging; nag means to run-on about something]

  ETE

RATING:    Three grins = Loved it; Two grins = Enjoyed it; One grin = A bit bland for my taste; One teardrop = Not much fun

[rbe]

Windows NT is an obsolete operating system meant for business use. It was released in 1993 and replaced by Windows 2000 in the year 2000. Not a good crossword clue.

[bbundy]

Oddly, 'NTS' has been graced by 7 appearances in NYT, all clued in this way.  I agree that it's an awful clue.  To me, replacing "IFTHEN", "AFFRONT" and "STOOGES" with "AFTERS", "ALFREDO", and "STOICAL", respectively, makes everthing work out rather nicely, also avoiding the undesirable directional clue at 114 across.

[SJS]

It seems to me NTs could be clued as "Some NFL linemen" - i.e., nose tackles, who line up across from the center.