Who should be VP?

Should it stay Cheney, or should Bush replace him? I am in favor of replacing him, for numerous reasons, among them health and political. The GOP, if it wants to be serious about security, needs to nominate a VP candidate who isn't likely to keel over. Also, Cheney is viewed even more negatively than Bush, and that isn't good. Someone needs to replace him, someone to keep people excited and hopeful.