Sir my Eclipse Release Version is 3.3.1.1 & plugin is HibernateTools-3.2.4.GA-R200905070146-H18, OS : Windows Vista Home Basic 32 bit.
I solved that problem of Hibernate.cfg.xml file by passing as parameter to Configuration.configure (), But the when ever i am opening the Hibernate Perspective i am getting the same execption..

Sir now my Project is getting execption as

Buildfile: D:\SUMIT\workspace\helloworld\build.xml
clean:
[delete] Deleting directory D:\SUMIT\workspace\helloworld\bin
[mkdir] Created dir: D:\SUMIT\workspace\helloworld\bin
compile:
[javac] Compiling 3 source files to D:\SUMIT\workspace\helloworld\bin
copymetafiles:
[copy] Copying 4 files to D:\SUMIT\workspace\helloworld\bin
run:
[java] Nov 19, 2009 8:48:12 PM org.hibernate.cfg.Environment <clinit>
[java] INFO: Hibernate 3.2.5
[java] Nov 19, 2009 8:48:12 PM org.hibernate.cfg.Environment <clinit>
[java] INFO: hibernate.properties not found
[java] Nov 19, 2009 8:48:12 PM org.hibernate.cfg.Environment buildBytecodeProvider
[java] INFO: Bytecode provider name : cglib
[java] Nov 19, 2009 8:48:12 PM org.hibernate.cfg.Environment <clinit>
[java] INFO: using JDK 1.4 java.sql.Timestamp handling
[java] Nov 19, 2009 8:48:12 PM org.hibernate.cfg.Configuration configure
[java] INFO: configuring from file: hibernate.cfg.xml
[java] Nov 19, 2009 8:48:12 PM org.hibernate.cfg.Configuration addResource
[java] INFO: Reading mappings from resource : hello/Message.hbm.xml
[java] Nov 19, 2009 8:48:13 PM org.hibernate.cfg.HbmBinder bindRootPersistentClassCommonValues
[java] INFO: Mapping class: hello.Message -> MESSAGES
[java] Nov 19, 2009 8:48:13 PM org.hibernate.cfg.Configuration doConfigure
[java] INFO: Configured SessionFactory: null
[java] Nov 19, 2009 8:48:13 PM org.hibernate.connection.C3P0ConnectionProvider configure
[java] INFO: C3P0 using driver: org.hsqldb.jdbcDriver at URL: jdbc:hsqldb:hsql://localhost
[java] Nov 19, 2009 8:48:13 PM org.hibernate.connection.C3P0ConnectionProvider configure
[java] INFO: Connection properties: {user=sa, password=****}
[java] Nov 19, 2009 8:48:13 PM org.hibernate.connection.C3P0ConnectionProvider configure
[java] INFO: autocommit mode: false
[java] Exception in thread "main" java.lang.UnsupportedClassVersionError: Bad version number in .class file
[java] at java.lang.ClassLoader.defineClass1(Native Method)
[java] at java.lang.ClassLoader.defineClass(Unknown Source)
[java] at java.security.SecureClassLoader.defineClass(Unknown Source)
[java] at java.net.URLClassLoader.defineClass(Unknown Source)
[java] at java.net.URLClassLoader.access$100(Unknown Source)
[java] at java.net.URLClassLoader$1.run(Unknown Source)
[java] at java.security.AccessController.doPrivileged(Native Method)
[java] at java.net.URLClassLoader.findClass(Unknown Source)
[java] at java.lang.ClassLoader.loadClass(Unknown Source)
[java] at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
[java] at java.lang.ClassLoader.loadClass(Unknown Source)
[java] at java.lang.ClassLoader.loadClassInternal(Unknown Source)
[java] at java.lang.Class.forName0(Native Method)
[java] at java.lang.Class.forName(Unknown Source)
[java] at org.hibernate.connection.C3P0ConnectionProvider.configure(C3P0ConnectionProvider.java:92)
[java] at org.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:124)
[java] at org.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:56)
[java] at org.hibernate.cfg.SettingsFactory.createConnectionProvider(SettingsFactory.java:414)
[java] at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:62)
[java] at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:2009)
[java] at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1292)
[java] at persistence.HibernateUtil.<clinit>(Unknown Source)
[java] at hello.HelloWorld.main(Unknown Source)
[java] Java Result: 1
BUILD SUCCESSFUL
Total time: 2 seconds
i have only Jdk 1.5 installed in my system no other jdk or Jre is there
Can u Please Help me out Thanks In Advance.....

I have downloaded all the jar from Hibernate site and simply attached it i dont how it is being complied with 1.4 since i dont have jdk 1.4 in my system . how can i get out of this ??

im pretty sure you somehow have enabled java 6 on your project but is running with a java 5 runtime. that would give such error.