in which folder have you installed your sed.exe? Lets assume it is in "C:\Program Files\Gnu\Sed\", than you should change the bat-file like this to ensure your sed.exe is found (this is what I meant by "change the path"):
@echo off
set infile=%1%
"C:\Program Files\Gnu\Sed\sed.exe" -e "s/;/\[\/td\]\[td\]/g" "%infile%" > temp1.txt
"C:\Program Files\Gnu\Sed\sed.exe" -e "s/$/\[\/td\]\[\/tr]/g" temp1.txt > temp2.txt
"C:\Program Files\Gnu\Sed\sed.exe" -e "s/^/\[tr\]\[td\]/g" temp2.txt > temp1.txt
echo [table] > table.txt
type temp1.txt >> table.txt
echo [/table] >> table.txt
del temp1.txt
del temp2.txt
-crono
It finds SED all right now (online armor requested permission to start it) but: a command window opens, closes and nothing else happens ...
the batch file is correct, I've checked it again and again
I copied sed.exe path into file in quotes as you show - it was in C:\Program Files\GnuWin32\bin\sed.exe (just in case)
command window said it couldnt find file path - broke it up in two parts actually, so I moved both files/folders up the tree a bit but now the command window shows completely blank
Is it important where the files are, and where in relation to each other ?