ok im not really infoed on the impact of hertz on a tv
but i can tell you that 1080 tvs are better than 720
because and i have seen the picture difference in person
the 1080 will show hd clearer than 720 even though only 720 is the highest actually broadcast inas for reg tv channels i dont know if some of the hd tvs dont have this but my tv actually upgrades the picture quality of what its broadcasting as does my dvd player now it doesnt brign the quality of the reg channels to hd but its better than they normally are and my hd tv is an lcd
so ask about that if you go searchign for an hd tv
and look at the pictures sometimes you can clearly see the difference =]
one more thing sometimes the reason your tv is blury is because your not watchign from the optimal distance if your watchign from too close it will be abit blury sometimes