I just got my first HDTV and I wanted to do the exact same thing. However, carefully reading the TV's manual (Samsung TX-P2775), they specifically mention that computer DVI signals will not display on the HDTV. I haven't tried it myself yet to prove this (I just got a male-to-male DVI cable for this yesterday), but it's entirely possible that the receiver in the TV is not made to interpret DVI signalling from a computer, only from other video devices.
Steve