I'm using distributed builds with UNIX machines.
But for one project I need to use windows machine (need some windows DLL for build)
I configured Windows slave machine using Cygwin sshd.
So I can perfectly execute on cygwin shell:
--------
$ /usr/local/ant/bin/ant
Buildfile: build.xml does not exist!
Build failed

ram@TORTUGA ~/workspace
$ /usr/local/ant/bin/ant -version
Apache Ant version 1.6.5 compiled on June 2 2005
----------

But hudson job fails with following error:

/usr/local/ant/bin/ant all -Dhudson.checkout=true
FATAL: command execution failed
java.io.IOException: CreateProcess: \usr\local\ant\bin\ant all
-Dhudson.checkout=true error=3
at java.lang.ProcessImpl.create(Native Method)
at java.lang.ProcessImpl.<init>(ProcessImpl.java:81)
at java.lang.ProcessImpl.start(ProcessImpl.java:30)
at java.lang.ProcessBuilder.start(ProcessBuilder.java:451)
at java.lang.Runtime.exec(Runtime.java:591)
at hudson.Proc$LocalProc.<init>(Proc.java:79)
at hudson.Launcher$LocalLauncher.launch(Launcher.java:168)
at hudson.Launcher$RemoteLaunchCallable.call(Launcher.java:252)
at hudson.Launcher$RemoteLaunchCallable.call(Launcher.java:236)
at hudson.remoting.UserRequest.perform(UserRequest.java:57)
at hudson.remoting.UserRequest.perform(UserRequest.java:22)
at hudson.remoting.Request$2.run(Request.java:178)
at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:650)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:675)
at java.lang.Thread.run(Thread.java:595)