Our need is to be able to convert an abitrary UTC time to local time (and vice versa) for an arbitrary US county or country in Europe. what I mean by arbitrary time: any date back to a cutoff of 2001/01/01 -- not just "today" or "right now". that's what made it messy: the rules for when DST turns on and off have changed through the years, and they don't change uniformly in space. Indiana is a case of this, and worse: some counties there even changed timezones in Apr 2006! To implement this logic twice, and maintain two codebases for it, was a cost I was not willing to pay.
We haven't experienced any problems with our solution. we didn't download it off the web though - built it in house. maybe that's where your problem was. you get what you pay for.
i'm curious to see what you did in t-sql though.