I don't think being a conservative and being an internationalist are mutually exclusive, since free trade's right out of classic economic theory. Bush is all over the map ideologically, though. Most successful politicians are.
I think our definition of conservative and liberal in America are all wrong. Most conservatives I know are really reactionaries (want things to go back to the way they were in the 1920s or 1950s), and most of the liberals I now are actually conservative (want things to stay they way they've been since the Great Society). This, of course, is partly because the Democrats haven't had a new idea since 1972. I sometimes call myself a liberal, but in reality my political hero is a man who left the White House over a half century ago.