I usually start by copying something else, and then changing/improving it until it looks how I want. I'm a not-designer as well, and don't have much artistic sense, and honestly cannot be bothered spending days (weeks) creating a UI for an application; it is much easier to just take something else and spin it how I like.
The MSDN blogs are usually a good place to look for inspiration, since many of the writers like to pimp applications/websites that use their favourite technologies (Brad Abrams' blog is good if you're looking for WPF-ish interfaces).
