I now have b3 working without the need of a .bat
navigate to your b3 install folder and type:
mklink /h python.exe C:\Python25\python.exe
Set the exe to python.exe
Commandline to b3_run.py -c b3/conf/b3.xml
Symlinking baby, its whats for dinner.
basically you are telling Windows, make a file called python.exe and point it to C:\Python25\python.exe
http://en.wikipedia.org/wiki/NTFS_symbolic_link
Wish there was a way to do this without having to but, its doesn't waste a task like a .bat does. So you gain a tiny big of resource savings. It may not make a difference if its only a few b3 instances, but as they grow, it will add up.
Edit: It looks like 2k3 machine may require a different command.
Look into fsutil hardlink create