First, apologies for not having the rewrite on the running total article done, yet.

Part of the reason it's not done yet is I've been testing the heck out of some very large examples. In the process of doing that, I've determined that specifying the index hint is absolutely NOT necessary on single table Quirky Updates. You do, of course, need a clustered index for the update to follow and it must use a 3 part update as well as following some other simple rules. Another of those rules is that it must be a single table update. By that I mean, no joins... period.