newbie question: I want libexpat.a but it's building libexpat.la

I am trying to build "libexpat.a" on a iMac with System X10.3.9, when I 
run "./configure --disable-shared --enable-static" and then run "make" 
it generates "libexpat.la", all the other packages that I am using 
generate "libxxx.a", and I don't know what a ".la" is.

I'm using g++ to generate my program, is there a way to use the ".la" 
file with it or do I need to somehow convert it to a ".a" file?

Thanks very much,
Kevin