The Mindcrack server.zip downloaded from feed-the-beast.com should be ~33MB, once extracted ~36MB. After starting it for the first time it should be ~41MB. Otherwise it could be a corrupted download.
Also, can you post a server log? When you start your server from ServerStart.bat, it should say stuff like Mod Initialized, Liquid Registered, Stuff Loaded etc.
Your server log is that ForgeModLoader-server-0.log or ForgeModLoader-server-1.log. Find the most recent one and post it on Pastebin.