I have a Kuhn-Rikon (Duromatic) that I love. It cooks around 5 quarts. I
agree with Holly, think about size. I need this size to cook the big pots
of soup I like, but I'm planning on buying a smaller one for cooking grain
pilafs, risottos, and small quanties of beans. Choose a stainless version
with a nice thick heat dispersing bottom and the modern safety valves. This
is one item you don't want to buy at a garage sale. There are lots of
decent brands to choose from now. I wonder if Vegetarian Times has reviewed
them?
Lorna Sass' cookbooks are great for learning to cook with a pressure cooker.