Plugins not loading - Mac OSX 10.4

I'm getting the following error when my server starts:

Is this because Java is outdated? Or are the plugins not compatible with the new bukkit build yet?

On OSX 10.4. running Java 1.5.0_19

Edit: Here is the full text...

Code:

09:00:01 [SEVERE] Could not load 'plugins/Essentials.jar' in folder 'plugins':
java.lang.UnsupportedClassVersionError: Bad version number in .class file
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:36)
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:24)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:242)
        at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:171)
        at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:215)
        at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:136)
        at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:152)
        at org.bukkit.craftbukkit.CraftServer.<init>(CraftServer.java:128)
        at net.minecraft.server.ServerConfigurationManager.<init>(ServerConfigurationManager.java:52)
        at net.minecraft.server.MinecraftServer.init(MinecraftServer.java:147)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:406)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:465)

Anyone?

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

Update essentials

 

I just downloaded it for the first time, I thought it was the latest version.

Can you tell from the error that I posted, that it needs to be updated?

 

I can tell that something needs updating. Updating Essentials is the best place to start, if that doesn't work then you should update CraftBukkit, then if that doesn't work update Java (although that would be difficult in your situation)