I don't live in your state, but how much did Corker beat Ford by? Rudy may not win the Repub Primiary in your state, but he could win the electoral votes. The last two elections a republican beat a democrat in Tennessee and as you know, Gore even lost his home state (did he ever live there, really, to Bush).
You don't have to feel guilty at all. If you choose not to vote, that's up to you. But then, you'll really have no right to complain about President Hillary in 2009.
Voters in Tenn. are weird! They would not vote for a Democrat for president, but will load up the local, state and congress with rats.
My guess is that the Evangelicals will stay home if Rudy is the nominee.