AUTOEXEC.NT isn't all that important, and shouldn't be in the Windows directory, as far as I know, I've always seen it in the System32 folder in all my installations. It's just a batch file though, so you can edit it in Notepad. Here's what it should look like:
REM AUTOEXEC.BAT is not used to initialize the MS-DOS environment.
REM AUTOEXEC.NT is used to initialize the MS-DOS environment unless a
REM different startup file is specified in an application's PIF.
REM Install CD ROM extensions
REM Install network redirector (load before dosx.exe)
REM Install DPMI support
REM The following line enables Sound Blaster 2.0 support on NTVDM.
REM The command for setting the BLASTER environment is as follows:
REM SET BLASTER=A220 I5 D1 P330
REM A specifies the sound blaster's base I/O port
REM I specifies the interrupt request line
REM D specifies the 8-bit DMA channel
REM P specifies the MPU-401 base I/O port
REM T specifies the type of sound blaster card
REM 1 - Sound Blaster 1.5
REM 2 - Sound Blaster Pro I
REM 3 - Sound Blaster 2.0
REM 4 - Sound Blaster Pro II
REM 6 - SOund Blaster 16/AWE 32/32/64
REM The default value is A220 I5 D1 T3 and P330. If any of the switches is
REM left unspecified, the default value will be used. (NOTE, since all the
REM ports are virtualized, the information provided here does not have to
REM match the real hardware setting.) NTVDM supports Sound Blaster 2.0 only.
REM The T switch must be set to 3, if specified.
SET BLASTER=A220 I5 D1 P330 T3
REM To disable the sound blaster 2.0 support on NTVDM, specify an invalid
REM SB base I/O port address. For example:
REM SET BLASTER=A0