First, I'm confused as to why you were expecting CFLAGS and CHOST to match? Those are two separate variables dealing with two different things... Anyway, I'm not entirely sure about your computer's setup, but I would leave CFLAGS as is unless it is giving you a problem. the i486 that's in it now simply refers to one of the newer of the Intel processor families, which if I'm not mistaken is what your P4 belongs to. If you experience any problems with make with CFLAGS unchanged, then would be the time to look into changing it.
Happy Hunting :-)