I saw the Heston movie long before I actually read the book. And what made the book so memorable was the "I am legend" part, where the human became a monster of lore to the mutants, just like vampires and werewolves were myth and lore to the humans (which in turn begged the question "were they real too?"). Anyway, that's what I liked most about the book, not the survival aspect of it.
And yes, Will Smith movie looks promising. I just can't help but wonder if they'll stick closely to the book or veer off and lose all that backstory. Just finished reading "Point of Impact" after watching "Shooter", and the book is just so much better.
And I too like the postapocalyphic movies, but what I always dislike the most is how it usually ends up being "hey, I'm the last man on earth, everything is mine!", with supermarkets full of food (and no horrible stench from meat/fish department), which was so nicely shown in "28 Days Later".