Trying my first installation.  From the Wiki, using a vanilla server, I was told to drop them into the same folder, change the extension, and run the file.  Running the file produced an exception, so I popped into a command line, and ran it from there.  The error message it threw was:

 

Exception in thread "main" java.lang.NoClassDefFoundError:ab

        at java.lang.ClassLoader.defineClass1(Native Method)

        at java.land.ClassLoader.defineClass(Unknown Source)

        at java.security.SecureClassLoader.defineClass(Unknown Source)

        at java.net.URLClassLoader.defineClass(Unknown Source)

        at java.net.URLClassLoader.access$100(Unknown Source)

        at java.net.URLClassLoader$1.run(Unknown Source)

        at java.net.URLClassLoader$1.run(Unknown Source)

        at java.security.AccessController.doPrivileged (Native Method)

        at java.net.URLClassLoader.loadClass(Unknown Source)

        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)

        at java.lang.ClassLoader.loadClass(Unknown Source)

        at sun.launcher.LeauncherHelper.checkAndLoadMain (Unknown Source)

Caused by: java.lang.ClassNotFoundException: ab

        at java.net.URLClassLoader$1.run(Unknown Source)

        at java.net.URLClassLoader$1.run(Unknown Source)

        at java.security.AccessController.doPrivileged(Native Method)

        at java.net.URLClassLoader.findClass (Unknown Source)

        at java.lang.ClassLoader.loadClass (Unknown Source)

        at sun.misc.Launcher$AppClassLoader.loadClass (Unknown  Source)

        at java.lang.ClassLoader.loadClass (Unknown Source)

        ... 13 more

 

Using the latest Minecraft server executable from MineCraft.net, and the latest version of universal off of the most recent forum version announcement (minecraftforge-universal-1.5.1.7.7.1.611.zip, also tried ~.651.zip)

 

Further, I reinstalled Java, and rebooted the computer, so nothing else might have been running in the background, in conflict.  No mods  are installed  yet, the server is still fresh, unaltered from its base state.  Installation client-side went smoothly.

 

Searching on the forum showed another user with a nearly identical problem, but without a response.  Takes a while to transcribe this, if you need more information, feel free to ask.

 

Edit:  Apparently, this is the error you get when it can't find the ab.class file during execution, because the files aren't in the same folder, or if you downloaded the server executable file (.exe) rather than the server java executable (.jar) from Minecraft.net

I'm assuming that file would be generated as the server is running with the Forge alongside the server.  My error is an installation error.  It generates no files.  The error I posted was the thrown exception when I was following the installation instructions, so Forge itself has never had a chance to run, or generate a ForgeModLoader-Server-0.log file.

Yes you need to jar for the server, not the exe. Always use the jars.