Test the waters with MIT OCW (http://ocw.mit.edu http://ocw.mit.edu) and Academic Earth (http://academicearth.org http://academicearth.org) for lots of lectures

Test the waters with MIT OCW (http://ocw.mit.edu http://ocw.mit.edu) and Academic Earth (http://academicearth.org http://academicearth.org) for lots of lectures & problem sets, and then make the jump if you feel that'll make you happy.