I think the biggest issue people have with HD is when it is viewed on older screens, either external, or built in to a laptop. There are still a large portion of 4:3 (Traditional television format) screens in use, even the new iPad and some other new tablet devices are basically 4:3.
The biggest advantage HD gives you is image clarity - many of the former videos were 480x360 pixels and in order to play on a 1024x768 screen (which was pretty standard) the image had to more than double to fit the screen. One pixel of video equals 2.2 of screen or something like that. Next the movies were 640x480 pixels which is basically VHS resolution - still not nearly the pixel density of a standard monitor. HD basically delivers images at much closer to a 1:1 ratio to newer 16:9 more pixel dense screens.
The other issue is aspect ratio - the old format was 4:3 which makes great use of older 4:3 screens - of which there are very few anymore (try buying ANY 4:3 television or monitor anywhere other than the Salvation Army or a pawn shop.) So, when I play a 4:3 video on my widescreen laptop i have giant black bars up the sides - it's called "pillar boxing" and when you play 16:9 on your 4:3 screen you'll have almost 2/3 of your screen black due to "letterboxing."
I'm not sure what the memory chip from HP that KingSurf mentioned has to do with the way TV screens and LCD panels are manufactured, but I can tell you that until every screen manufacturer and video camera maker comes up with something new (and the cycle to implement and create standards can be well over 10+ years) HD is here to stay.
If you're looking for a high quality screen than can double as a computer monitor and a screen for BluRay or other newer formats, consider a Samsung LED monitor - they are reasonably priced have a very nice image and most include both HDMI ports (the new single-cable digital format for HD video and audio), a VGA port (for older analog PC video), and a DVI port (for newer digital PC video) among others. Just make sure it includes speakers if you are using it for BluRay or that type of thing, as not all of the monitors include them.
Sorry to get all didactic, but people really seem to get confused around new video formats, hardware and software. There is so much mis-information out there (much of it seems to come from electronic store employees eager for a sale...)
Good luck.