Which version of windows XP does Visual Studio 2012 supports. [Edit: Which version does VS12 supports compiling to]
I found this article: http://blogs.msdn.com/b/vcblog/
It's correct, Visual Studio 2012 can compile binaries compatible with Windows XP SP3.
You need to install the Platform Toolset v110_xp and select it in the general configuration properties of your project.
If "safe" means that it works the answere is yes. We have 12.000 installations of our software compiled with Visual Studio 2012 (and recently Visual Studio 2013) perfectly working on Windows XP SP3.
The only big problem is run time debugging: you can't install Visual Studio 2012 on Windows XP so it could be a problem to find bugs that accidentally happens only on Windows XP.