Complex sentence: Courtney Hansen was the co-host of the show from the inception, when in 2005, she left the show to pursue other interests, landing hosting duties on Spike TVs Powerblock (which includes rival shows Horsepower TV and MuscleCar).
Split into simpler sentences: Courtney Hansen was the co-host of the show until 2005, when she left the show to pursue other interests. She landed hosting duties on Spike TVs Powerblock (which includes rival shows Horsepower TV and MuscleCar).