Actually, electing conservatives to congress is just as important, if not more so. We will need conservatives in congress to control the evil twin brothers of both the presidential candidates.
Republicans in congress are not enough because many of them will support their president if McCain is elected, even when he is terribly wrong, as will most of the democrats, because he is terribly wrong.
We need conservatives who will stand up to whoever wins. One senate seat could make a huge difference in defining how bad the next four years will be.