You can do almost anything with VB on windows, the plus sides of VB is its quite easy to Learn (Comparing to other Languages like C, C++), It has one of the Best Integrated Development Environments, Building interfaces with it is probably the easiest among many other Visual Programing Languages, Down sides are, VB is not Speedy like say C++ or Delphi, VB6 is much faster than VB.net tho, You can only program windows Applications using VB (ie no Linux, No you cant make OS's with VB lol), IT depends on other runtime DLL's to do what it do, Id say you should learn some thing like C++ first hand and then move to VB (when you master C++ you probably dont want VB)
But you can make Fairly complex software with VB,