Most macros will work fine. But it also depends on what you're doing. There
have been several things which are no longer supported in excel 2007, but
they were "deprecated" because so few people used them anyway, so you're
probably ok. Time to bite the bullet.
And preferably installing it on a virtual hd since virtual pc is free of
charge these days so the OP doesn't mess up anything if he wants to go back
to 2003