LaTeX question

[Novak Elliott]

does anyone know how to use \marginpar{} in conjunction with the eqnarray*
environment. I want the margin note to be adjacent the final equation. 
ie

                A = B   |
                B = C   |
        :.      C = A   | C = A

beginning of margin     ^

all i can get is:

                A = B   |
                B = C   |
        :.      C = A   |
                        | C = A

by having the \marginpar after the equations, it wont let me put it in the
equation.

thanks in advance,
Novak.