alt pc<->opt mac key translation

[Christopher Smith]

Can anyone point me to the resource to help me figure out what alt key 
combination corresponds to what option modified keypress on the mac?  e.g. 
if I press option-m on the mac (µ) what is the equivalent alt#### on the
pc 
and vice versa?

I checked out the unicode.org web site and downloaded some of the key maps 
but am not sure I am interpreting them correctly.  e.g.  I have a file
that 
I know someone type alt-0218 in; on the mac this looks like a capital U 
with an accent; in the unicode tables this character has code 00DA, not 
0218.

/c