Well I took the plunge today and got a HD DirecTV box.
I've had a HD capable set (with a tuner) for about a year now but have never seen anything in HD on it yet!
The final push was watching the first season DVD set of "Lost", I couldn't stand the idea of watching the second season in SD.
This is one of the best show's ever and it's filmed in widescreen on location in Hawaii and is a perfect showcase for HDTV.