rmathew: Just read SICP, it's great. For a LISP interpreter there is the MIT one of course (SCHEME). But that one only works from within a GUI. A commandline Scheme is PLT, use "MzScheme.exe -r %*" in a .bat file for the CMD shell (assuming you are using Windows).
And there is CLISP, which is NOT Scheme! But on Windows that is not so easy to use from the commandline, you have to do something like this in a .bat file:
@d:\clisp\base\lisp.exe -M d:\clisp\base\lispinit.mem -B d:\clisp\base\ %*