Terminal server or not?

Our six-office WAN currently has in place the traditional application-loaded client model. Of course, this is fraught with such issues as constantly upgrading the client machines, handling upgrades, etc. We are considering going to the Terminal Server 2000 model - virtually any PC can access the corporate server and applications, we can lock down the client machine from users installing apps, etc.

There is a major expense making the change and a major shift in direction to consider for both IT staff and users (not to mention corporate management). Have you shifted to a "dumb terminal" environment? How was the transition, from technical to attitudinal? Does it really save time / effort? How do you handle crashed servers (that is, do you cluster)?