I noticed that many people have already provided the same answer I would which is "Express". Just wanted to chime in and say I agree all you need is express, also let me elaborate a bit more hopefully to help you understand what the true differences actually are.
In C++ you write code an run it through a compiler with potentially a slue of additional commands linking to external libraries and what not. As such you technically don't need an IDE (Such as Visual Studio), you just need to write your code and run it through the compiler with the correct command's. The reason that most if not all professional programmers choose to use an IDE is because it greatly simplifies the coding procedure through using intellisense (auto completion & popup tips), syntax highlighting (the colors) and allows you to point and click your settings that are later fed into the compiler as the proper commands.
With that said we get to the differences between professional and express versions of visual studio. Most simply, the express version is everything you need to code and compile your programs, it's ready out of the box. The pro versions allow you to install and use mod's and plugins that extend how the IDE itself works. In most cases they don't particularly make any difference to what you code or create. Examples would be like including SVN, Git or Preforce project collaboration. It can be nice to have some of these extra plugins, but if you can't afford or simply don't want to pay for pro... don't. It's not like your game itself will be any different if you make it with express or pro.