I dont know for certain but I would assume the the icons etc, will be about the same size as on a 15in tft at 1024x768, as the pixels in general tend to be smaller than on a 15 inch so you should also get a sharper picture.
As for gaming and DVD's so long as it has a refresh rate of 30ms or less it should be fine, as though not an avid gamer I have the odd go on SOF II and find it no worse then when I was playing it on a 17 inch Mitsubishi diamond pro 730. I'm now using 15 inch tft with a 30ms response time.
Yes the text will be smaller on a 17" TFT compared with a 15" TFT, also the Icons.
Movie's and games play superb on a TFT. In fact because of the lack of reflections and the quality of display, I would say they are better, others will disagree, and it is a personal opinion as to which is better.
Pop into PC World and watch a movie on a TFT, you will see the quality for your self. Regards. j.