My story is similar. I had an Olympus 8080WZ for a few years, and gradually became frustrated with its limitations. I had to get an SLR.
I researched the market thoroughly, and the K20D simply offered the best bang for the buck (by far) of the enthusiast-class SLRs. Most people seem to think that you can't go wrong following the Canikon herd, but I'm inclined to gravitate towards the brands with less market share -- I figure that they'll try harder to get and keep my business.
Since I've made my purchase I've gradually come to appreciate many of the things that make Pentax cameras special. There's absolutely no buyer's remorse here!