Fiscally, perhaps, but not socially. I think when it comes down to it, the social issues are what best define conservatism at the foundational level.
Social conservatism will be the death of the GOP because it is such a turn off to most of the voting population. If the GOP ever ran on a purely social conservative platform (see Alan Keyes), they would start getting about 25% of the vote.
The current GOP politicians run as conservative in both fiscal and social matters but then govern as fiscal liberal/social conservatives. They get away with it because the democrats run as fiscal moderate/social liberals but then govern as full blown socialists.
If the only difference between Kerry and Bush had been that Bush was a social conservative and Kerry was a social liberal, Bush would have lost in a landslide. Tax cuts and national defense are powering the GOP right now.
The GOP is about to lose out on both issues as the president's policy on immigration is destroying his national defense credibility and his fiscal liberal tendencies are destroying any economic benefits of the tax cut.
Unless the GOP starts governing as fiscal conservatives, it will lose at least the senate in 2006 and the white house in 2008.