I tend not to ride in the rain, but maybe this option will help...

My winter tights of choice are REI's Power Stretch Tights (http://www.rei.com/product/48032737.htm). I wear them over a pair of bike shorts. The outside of the fabric is smooth, the inside is fuzzy. While they are not waterproof, light rain/snow tends to run off, and my legs have stayed pretty dry.

If I'm caught in the rain (or decide to break my own rules about starting out in the rain), I picked up an as yet to be tested layer that looks very interesting: http://www.rainlegs.co.uk/. At the time I bought mine, they were not yet available in the US (and I think that's still the case), but shipping from the UK was fast (I had them in 3 days) and surprised me by ending up in my mailbox without any customs due.

--- Denise