OK
After you download and install Ghostscript 8.54 into C:\Program Files
AND copy your PS files into C:\temp\ps
AND they are all letter size
AND you don't mind that the pdf's will all be named [yourfilename].ps.pdf
Do this:
for %i in (c:\temp\ps) do C:\progra~1\gs\gs8.54\bin\gswin32c -q -dSAFER -dNOPAUSE -dBATCH -sPAPERSIZE=letter -sOutputFile=%i.pdf -sDEVICE=pdfwrite -c .setpdfwrite -f %i
OK?