I don't have Vista/O2007, but Office didn't use to be skinable on its own as
far as i know, so try the system display settings. Control
panel/display/appearance. You could also look for ready-made themes and
replace the default one with something more to your liking. But all that will
affect all programs, not just Office.
Ok, I was wrong. You can skin Office now, so why don't you search the web
for Office 2007 skins?
From the looks of it, however, that may be an exercise if futility; I for
one have not been able to find other skins. So it looks like you are stuck
with what's included for now.