Finding good pants for winter biking
It really depends on your budget, but you should check this out (or anything similar), from Gore bike wear :



179.99 USD MSRP http://www.gorebikewear.com/remote/Satellite/PROD_TULTRO?landingid=1208436873480O

They aren't the tightest pants out there, but "real" tight pants are very rarely (trying not to say never) waterproof because of the type of fabric used to make them.

An alternative idea would be a nylon pant (waterproof, windproof, but absulutely not warm) that's relatively tight with a warm baselayer.