Design pattern for components that depend on each other

We create a "configurator" application for pipelines. Basically, the user walks in and selects a model, and then starts assembling the parts they want. Some components have dependencies on other components. For example. if I select Part A then I need to select 1 or more Part B. This is somewhat similar to setting up a PC on Dell.com. The app will also provide suggestions for parts / components.

Based on this information, I am investigating if there is an existing model (s) that would allow us to simplify its maintenance and design. Any thoughts, ideas? Are there any open source projects that have similar functionality I can borrow ideas / patterns?

I'm more interested in how to define "rules" between components without hard coding the rules / dependencies.

Thanks for any help.

Not that it matters, but we are building this in .NetFramework 3.5 / Asp.Net