I was reading through some programming books and read about Lua. Lua is a completely free scripting language. Even for commercial use. Basically the only thing you have to do is to mention it in a readme, and if you want to be really cool, add the Lua logo to your game.
Lua is based on ANSI C. It should compile on any platform. This means that if you ever try to port your game to linux, you don't need to change scripts. Also, Lua can be compiled or just "plain text". If your code (Script) is plain text, Lua will compile it on the fly when you load it in your game.
If you like to see compile errors, and have a compiled script, simply use the command line utility. You do not have to change any code to load "text" or binary Lua files! So, if you're done developping: Compile the Lua files and replace the text versions, and it should work just fine.
The main site of Lua is www.lua.org. Check it out for some more details.