I have a pair of waterproof trousers much like those posted by throttled, keep them in my locker at work and have a 2 piece Frank Thomas waterproof set, removed the thermal liner from th FT trousers and just wear them over my jeans. Use HG goretex boots and can ride all day in shitty Glasgow weather and still be dry at the end. I just bought it all during the sales one bit at a time. In general I look at the weather before my commute, if it looks like it's gona be shitty, I figure it will be and dress accordingly, i'd rather be a bit too hot than soaked and cold.