Thank you all very much for your replies! This has been helpful. Due to DavidLee's input on the waterproof panniers I chose not to get the Nashbar Waterproofs...I'm not the do-it-yourself type.
Due to other reviews of the backpack/pannier thing I decided not to get that either.
Due to the high price of high-quality panniers, which would be great, I decided not to get those either.
Since I have 2 waterproof backpacks already I decided to get a basket...I got a nice one from Kettler. With a bungee net.
Now I just throw my stuff in my bag, throw it in my basket, strap it down, bike, unstrap it, carry it inside.