Windows Vista / 7 and later

Windows Server 2003 and later

With a little effort you can use forfiles to get the last modified time of a specific file, seconds included:

REM "delims=" is required to avoid stripping AM/PM
for /f "delims=" %%i in ('"forfiles /m filename /c "cmd /c echo @ftime" "') do set modif_time=%%i
echo %modif_time%

Example output

7:33:54 AM

The value displayed is based on the local time of the computer and matches the time shown in the file properties dialog.

Usage help

http://technet.microsoft.com/en-us/library/cc753551.aspx

Windows XP

forfiles.exe is not available out of the box, however you can manually get the required executable. It's an old version which is part of the Windows 2000 Resource Kit. The syntax is case-sensitive and slightly different, and so is the output:

for /f %%i in ('"forfiles.exe -mfilename -c"cmd /c echo @FTIME" "') do set modif_time=%%i
echo %modif_time%

Example output

153354

Here the time value is displayed in the UTC format and is not affected by changes in time zone or daylight saving time. In this example the file was last modified at 15:33:54 (UTC).

Note You can obtain the newer forfiles.exe version by grabbing a copy of the file from any Windows 2003 Server installation or setup media.

Dbenham is right, your existing posted code should rename both files and folders. The only questionable point lays here: move folder folder with the same Source and Target might result to a breakpoint with The process cannot access the file because it is being used by another process error message (see an example in output below). Simple if /I could solve it as follows:

@echo off
SETLOCAL enableextensions enabledelayedexpansion
SET "old=ACK"
SET "new=XYZ"
for /f "tokens=*" %%f in ('dir /b *%old%*.*') do (
  SET "newname=%%~f"
  SET "newname=!newname:%old%=%new%!"
  if /I "!newname!"=="%%~f" (
        echo ==== "%%~f"
    ) else (
        echo move "%%~f" "!newname!"
    )
)
ENDLOCAL
goto :eof

Output:

==>D:\bat\SuperUser\881861.bat
move "ACKnowledge" "XYZnowledge"
move "assocbackup.txt" "assocbXYZup.txt"
move "ftypebackup.txt" "ftypebXYZup.txt"
move "StackOverflow" "StXYZOverflow"

==>move "ftypebackup.txt" "ftypebackup.txt"
        1 file(s) moved.

==>move "StackOverflow" "StackOverflow"
The process cannot access the file because it is being used by another process.

==>