Not silly, the discussion of breathable vs. non-breathable is NOT common knowledge. Here is the appropriate thread to discuss the differences, just in case anybody is planning in advance.

I wish I had the understanding before I learned the hard way. It took me a couple of uncomfortable ski seasons to hone in on WHAT materials to use and WHEN to use it. Plus, ski companies (e.g., North Face, 686, etc.) are always changing their products. It's good to have an understanding of what materials work, as opposed to buying a brand without the understanding.