Another "good" vote. I've used Kingston and Crucial in all of the systems I've built, and never had a problem. In fact, I just ordered a 512MB PC3200 stick this morning. Mushkin is supposed to be good too, but the one stick I've gotten from them so far - bought it last week - was a dud 🙁 Died after 4 days, and is in transit now for a replacement. They're still a good company though, considering how many good things I've read about them; as long as the replacement works, I will buy from them again.
Nathan