The Express versions
The free versions of Visual Studio are "degraded" version of their big brother, each dedicated to a specific task (or language for 2010 versions). "Degraded" because Express versions do not support the whole Visual Studio plugin ecosystem. They are great if you are on your own, or even within a small team of developers. They are freely available for 30 days and then require a free product key for ongoing use after 30 days (it takes only a few seconds to get the key, no big deal).
Both 2010 and 2012 versions are still available and nearly all compatible with Windows 7. The lone exception being Visual Studio 2012 for Windows 8 which is technically installable on Windows 7, but requires considerable human effort to be able to build Win 8 apps.
Depending on what app you want to write, here is how to choose:
- Windows Store (Win 8 and Win RT) apps:
- Visual Studio 2012 Express for Windows 8
- Desktop Windows/Console apps:
- Visual Studio 2012 Express for Windows Desktop (Silverlight and XNA too)
- Visual C++ 2010 Express (no WPF support, but COM+ support)
- Visual C# 2010 Express
- Visual Basic 2010 Express
- Web apps (ASP.NET, MVC 3/4):
- Visual Studio Express 2012 for Web
- Visual Web Developer 2010 Express
- Windows Phone (Silverlight 3/4, XNA) apps:
- 7.5/8 apps: Visual Studio Express 2012 for Windows Phone
- 7/7.5 apps: Visual Studio 2010 Express for Windows Phone
The full trial version
Note also that you can install trial versions of the Visual Studio 2012. If you are on your own it's overkill to try the "Ultimate" or "Premium" version. They all have a 90-day trial limit, which is pretty good I think to get a good feel about it, or even to conclude a small-sized project.
The "Professional" version contains everything you need to build apps for everything mentioned above, plus other types of apps more related to a "business" environment such as Sharepoint, Office, or Biztalk for example.