Black Holes and Resistance are an acquired taste I'd say. They both are very different from traditional rock Cd's.
Of course, Muse is much more than an average band, so you could start there and still love it, but a little knowledge of their more "popular" stuff will let you appreciate the band more.
So yeah, I'd say Absolution, then Origins of Symmetry, and Showbiz/Black Holes/Resistance afterwards.