Java Source Level for Web Services

I tried to create a simple web service using Netbeans 5.5. but its giving this error message underNew Web Services Wizard. and I can't continue.

To Create Web Services in this project, java source level must be at least JDK 1.5.

What is the meaning of this Error. And what should i do to prevent getting this error again.

Additional Inputs from my system:

C:\>java -version

java version "1.6.0_01"

Java(TM) SE Runtime Environment (build 1.6.0_01-b06)

Java HotSpot(TM) Client VM (build 1.6.0_01-b06, mixed mode, sharing)

[580 byte] By [Ajaxranda] at [2007-11-27 4:37:35]