If those bombs had gone off and killed the 400-or-so people in the canteen at the time, the bullshit backlash against the 'individualist loners' would probably have been even more intense than it was OTL, making my High School years even more difficult than they were already (post-Columbine attitudes weren't just restricted to America).
Other than that and possibly more backlash against computer games, I can't picture there being that many differences, especially in the long-term.