I've never understood why designer and common ancestry have to be mutually exclusive.
For a long time that was the position I took (mostly in my head) as well. Why couldn't evolution be the mechanism that "God" used to move species along? This was before I'd met a YEC type of believer - in fact at that point I didn't know there was such a person, much less many of them.
I'm currently taking two biology classes, a happy accident of "goal" requirements that worked in my favor. In one we're covering the uses and applications of plants, current and historic; in the other we're going through cell biology and evolution. Both classes are high level overviews, intended for non-science majors and it's been quite educational to blow the dust off of science I learned almost 30 years ago. There's so much more information to make sense of it's almost overwhelming, even with a professor to guide me. I can almost feel the new neural pathways being created when I make sense of a new piece of information that gathers up a number of random facts into a cohesive whole concept.
I only thought I understood biology and evolution before taking these classes. It's not even that my understanding was wrong so much as very incomplete in light of 30 years of research since I studied it. They've both filled in blanks in my data set that I didn't even realize were there. I'm actually finding it harder now to discuss evolution with theists here who want to argue about it - there's so many incorrect assumptions in their position that we often aren't even discussing the same thing. No disrespect intended to anyone posting in this thread, this is more of a general observation of what happens here so often.
Darwin (and another man named Wallace) are responsible for articulating the theory of natural selection. Natural selection is one mechanism by which evolution can occur. The terms are not interchangeable. They saw a pattern, and explained the process - that's what science is at it's core, an explanation of the evidence available. The scientific method is designed to guard against bias by requiring the questioner to identify whatever information would make their hypothesis wrong - intelligent design ignores any evidence that opposes it's hypothesis.
Once again, I'm reminded that my lack of god beliefs is not because of science, but science certainly has helped me back up my disbelief with better answers.