Eclipse novice here...

Thanks in advance to responding.
I have been developing with JBuilder 5.0 and using ANT to build my projects. I want to start using Eclipse. I installed it and try to run my build.xml file for ANT and I get the following error:
"Unable to find a javac compiler;
com.sun.tools.javac.Main is not on the classpath.
Perhaps JAVA_HOME does not point to the JDK"
Not sure what I have set up wrong. I have tried so many things to try and compile my project. Nothing seems to work, neither compiling or running ant (which works if I run it from DOS). I think it's an internal classpath setting with eclipse. Any suggestions to get me up and running with eclipse would greatly help (heard it's a great product).
Thanks,
jorge