You are correct in your understanding of the "Native resolution". A 17" TFT will give a display equal to a 19" CRT monitor, and there will be no flicker at all.
TFT's give a very clear and stable picture, with sharp text and graphics. But! In saying this, you will find the text/display is still a little on the small side due to the resolution rate.
A 15" TFT although smaller in display area, (Equal to 17"CRT) will give you a larger text and graphic output, in fact very similar to 800x600 on a 17" CRT. with no flicker at all.
Very easy and restful to the eye. Regards. J.