Java APIs

I have being developing using java j2sdk1_3_Orc3win full version from 23/04/00 using Windows98SE:From 29/03/03 I have up graded to Microsoft Professional Windows 2000 [Version 5.00.2195]and I am using NTFS.
Java 2 runtime Environment SE v1.4.1_02.
Java 2 SDK SE v1.4.1_02.

C:\>javac Welcome2 compiled ok. A class file is created.
C:\>java Welcome2 would not compiled.
C:\>Exception in thread "main" java.lang.NoClassDefFoundError: Welcome2
Press any key to continue . . .

Download the latest compressed on 4/04/03 the file was j2sdk_1_4_4_02windows-1586 and isalled fully.

C:\>javac Welcome2 compiled ok. A class file is created.

C:\>java Welcome2 would not compiled.

C:\>Exception in thread "main" java.lang.NoClassDefFoundError: Welcome2
Press any key to continue . . .

System variables: classpath%classpath%.;C:\j2dk1.4.1_02\lib\tools.jar
System variables: Path=%Path%;C:\j2dk1.4.1_02\bin

Test programme used to check out the :

public class Welcome2 {
public static void main( String args[] )
{
System.out.print( "Welcome to " );
System.out.println( "Java Programming!" );
}
}
This is my second temp to get some help on this subjest.