It appears that for some reason my computer thinks that .jar files are opened by explorer.exe. I am using windows seven and it will not allow me to change that program that opens it by default as a .jar file is a program and you cannot open programs with other programs.

you cannot open programs with other programs

What's a virtual machine, then?
In particular, what's the JVM if not a program?

Double-clicking is for wimps. Real men java foobar.jar

A .jar file is not a program, it's a Java Archive file. It's a zip file (IIRC you can change it to .zip and extract it with Windows Explorer but I haven't tried it) containing Java bytecode files, resource files and metadata. The JVM extracts the files inside and then uses those to run the Java code.

Oh, ok. But how do I change it back?

right click -> open as -> choose standard program

or something along those lines.

Yes, but it won't allow me to set it as default.

Do you have the privileges to do so?

Tools -> Folder Options -> File Types (TAB)
This should be where you set the file type affinities.