Blu-ray, true high definition?

I have recently bought a nice little blu-ray player, along with a couple of blu-ray discs. These are discs of relatively new programs and look the part, much more detail and a much sharper image. However, when I was looking in a video store, I saw a lot of older movies (such as close encounters of the third kind, the original terminator etc.) On the box, it promises a high defintion experience, but surely these films are recorded with older, non high defintion cameras. Is there any point in paying extra to have these films on a blu-ray disc when I can buy a standard DVD for a 3rd of the cost or do they do something with the video to make it high defintion? It seems a bit of a rip off and false advertising if its exactly the same video just burnt onto a diffrent kind of disc.

The movies you mentioned were filmed in much higher resolution than you apparently think. I suspect you are thinking since all appeared at one time or another on analog TV, that the films were low resolution. They were not. The film masters were high resolution and were altered to display on standard def TV. However, all they have to do for blu ray is to go back to the master and copy that.