Chances for getting into ivy/ good schools such as MIT/ CALTECH?

Unfortunately, schools don't look at your weighted GPA at all; only the unweighted counts. With a 3.73 and an 1840 on your SAT, I'm afraid you don't stand much of a chance at schools like that, which tend to expect near-perfection. You can certainly apply, but be sure to have some good back-up schools, because you would be a great candidate at a lot of schools. The ones you mention, however, tend to draw from a global marketplace and can afford to be extremely selective.