In terms of getting Enders working again for me, I had to add one extra bit of information to the .bat file - as running it from ..salem\bin\ folder just flashed up a black cmd line window before it closed without launching the game.
Problem for me was that the command in the .bat file couldn't locate my javaw.exe, (as there wasn't one in my salem\bin\ folder)
Solution is still exactly as described by Hans, except my .bat file now contains 2 lines:
path="C:\Program Files (x86)\Java\jre7\bin\"
javaw.exe -Dhaven.resurl="http://plymouth.seatribe.se/res/" -Dhaven.defserv="plymouth.seatribe.se" -jar salem.jar
Hope this is of help to anyone else with a similar setup (win7 x64) who might have been experiencing the same issue.
Yeah, that's what I needed as well. Thanks.