Spatial Normalization                  

There are a couple of ways to go about it with SPM.  The best way to explain it is through pictures (a picture is worth a thousand words, especially my non-eloquent words).  I'm not sure that there is a reason to do one way over another

1-  anatomical space based approach : Make all your images match the SPGR (since it has the highest resolution) and then use the SPGR to determine the appropriate normalization transformation.  Useful if you are going to use programs ourside of SPM.

2-  functional space approach :Make your SPGR image match the rest of your images, then use it to determine the parameters for normalization.  This is the most efficient way of doing it.