You will notice it alot more the bigger your screen is. In those tiny pics maybe it doesnt make that big of a difference (though there is a difference). But imo SDTV looks like crap on big screens.
With gaming, the important part for me is user interface and being able to read text. I bought knights of the old republic 2 for my 360 (xbox version) a few weeks ago since I hadnt played it, but I couldnt play more than a few minutes since I got so fed up with only seeing a small part of the screen and having to navigate all the low resolution menus, so I went and bought it for my pc instead to play it at higher resolutions.