I'm playing in a 1e campaign that started in 1983, though I didn't join it until '89. The DM decided to convert it as soon as 3e came out, but it's taking a little longer than expected (we've been on a fairly irregular and widely-spaced schedule).
While everyone wants to convert, and prefers most things about 3e, I'm not sure it's the best fit for the campaign and DM's style. The PCs range from 3rd to 10th lvl, he does a lot of it off the top of his head (even major, direction changing stuff), and there are a few other factors that make me wonder whether it can work quite as well. What we may actually need is a system that's far more rules-lite than either edition.