All the advice on Goretex (ie Paclite etc) is good - Grangers or Nikwax wash-in proofers are definitely worth a go. Also a top tip is to tumble dry it on a non-hot setting for a while. It makes the fibres on the outer fabric stand up and shed water more readily. Goretex does have its limits though, and in my opinion is not great stuff. It needs to be significantly warmer on the inside of the jacket than the outside to work properly, and also if it's too wet in the outside world then it just won't work as the moisture pushed through the jacket via the breathabillity has nowhere to evaporate to as the atmosphere is already full of moisture. The best garments I have ever used (and I don't work for them!) are made by Paramo. They don't pack up small enough for sticking in a back pocket on a bike, but if you want to stay dry they are the business - in all conditions. Ask anyone who uses Paramo what they think and they'll just tell you to go and buy one!