Add users to local Administrators group on multiple remote computers

Place computers.txt, psexec, & start.bat in a folder on the root of C:
STAR.BAT:

PSEXEC @COMPUTERS.TXT -u username -p password -d -e -h %WINDIR%\SYSTEM32\NET.EXE localgroup "Administrators" /add "domain/username"

Repeat the line above in START.BAT for each user or group that you want to add to the local Admins group.