I do not used windows. most of the coin description in GitHub source, After "make -f makefile.unix" will not be compile COINd files. I can not find a solution, even though I use google.
let's watch the command more closely :
"make" which means compile if you want.
"-f" it is a param who means force.
"makefile" it is the recipe.
".unix" means it is the unix makefile, made for debian, ubuntu ...
Look for the other makefiles, you have osx and mingw, sometimes people use their own makefile.
now, these files are not the only way to compile the client to windows, i know about four other ways :
-gittian builder
-mxe
-hand work
-mingw
I think it is enough for you to find how to do it.