[AndMetal]

This should also do the same thing with less "fluff":

ren "C:\Program Files\Sony\EverQuest\nektulos.eqg" nektulos.eqg.bak

However, it would have to be on the C drive and under the Sony folder (when EQ first came out, it was installed to "Program Files\EverQuest", which could pose a problem). You could make it a little more dynamic this way:

@echo off
CLS

ECHO Locating nektulos.eqg ...
ECHO.
IF EXIST "C:\Program Files\Sony\EverQuest\nektulos.eqg" GOTO C_SONY_EQ
IF EXIST "C:\Program Files\EverQuest\nektulos.eqg" GOTO C_EQ
IF EXIST "D:\Program Files\Sony\EverQuest\nektulos.eqg" GOTO D_SONY_EQ
IF EXIST "D:\Program Files\EverQuest\nektulos.eqg" GOTO D_EQ
IF EXIST "E:\Program Files\Sony\EverQuest\nektulos.eqg" GOTO E_SONY_EQ
IF EXIST "E:\Program Files\EverQuest\nektulos.eqg" GOTO E_EQ

ECHO Unable to locate nektulos.eqg!
GOTO END

:C_SONY_EQ
ECHO Found "C:\Program Files\Sony\EverQuest\nektulos.eqg!"
REN "C:\Program Files\Sony\EverQuest\nektulos.eqg" nektulos.eqg.bak
IF ERRORLEVEL 1 (ECHO Rename failed!) ELSE (ECHO Renamed nektulos.eqg to nektulos.eqg.bak)
GOTO END

:C_EQ
ECHO Found "C:\Program Files\EverQuest\nektulos.eqg"
REN "C:\Program Files\EverQuest\nektulos.eqg" nektulos.eqg.bak
IF ERRORLEVEL 1 (ECHO Rename failed!) ELSE (ECHO Renamed nektulos.eqg to nektulos.eqg.bak)
GOTO END

:D_SONY_EQ
ECHO Found "D:\Program Files\Sony\EverQuest\nektulos.eqg"
REN "D:\Program Files\Sony\EverQuest\nektulos.eqg" nektulos.eqg.bak
IF ERRORLEVEL 1 (ECHO Rename failed!) ELSE (ECHO Renamed nektulos.eqg to nektulos.eqg.bak)
GOTO END

:D_EQ
ECHO Found "D:\Program Files\EverQuest\nektulos.eqg"
REN "D:\Program Files\EverQuest\nektulos.eqg" nektulos.eqg.bak
IF ERRORLEVEL 1 (ECHO Rename failed!) ELSE (ECHO Renamed nektulos.eqg to nektulos.eqg.bak)
GOTO END

:E_SONY_EQ
ECHO Found "E:\Program Files\Sony\EverQuest\nektulos.eqg"
REN "E:\Program Files\Sony\EverQuest\nektulos.eqg" nektulos.eqg.bak
IF ERRORLEVEL 1 (ECHO Rename failed!) ELSE (ECHO Renamed nektulos.eqg to nektulos.eqg.bak)
GOTO END

:E_EQ
ECHO Found "E:\Program Files\EverQuest\nektulos.eqg"
REN "E:\Program Files\EverQuest\nektulos.eqg" nektulos.eqg.bak
IF ERRORLEVEL 1 (ECHO Rename failed!) ELSE (ECHO Renamed nektulos.eqg to nektulos.eqg.bak)
GOTO END

:END
ECHO.
PAUSE

This will search drives C, D, and E in both Sony\EverQuest and EverQuest for nektulos.eqg. It will rename the first one it sees and give some semi-useful output based on what happens.

I'm sure there's a way to make it even more dynamic, but that's a little over my head at the moment.