MathWorks, the makers of MATLAB, will be dropping support for 32bit Windows operating systems in the near future (“the next couple of years” in their words). MathWorks’ suggestion is for people to start moving to 64bit Windows on new systems. That will also allow your programs to address more memory, and is a good idea in general.
MathWorks also says that the last release of MATLAB that will support Windows XP and Windows Vista will be the R2014a version.
These changes in supported configurations can be an issue when people need to have software for a particular computing configuration. As an example, we recently had to dig around for the last 32bit Linux distribution for an older computer. (That version was R2012a, in case you need that.) We can (to some extent) get the appropriate version for your system
If you have ageing hardware and operating systems, you can find the last version of MATLAB that supports it at MathWorks’ Platform Roadmap.
As an aside, it always a good idea to note the version of all software packages that you’re using in your research. There may be “peculiarities” (okay, bugs) associated with certain versions that can affect your results. Those peculiarities will cause problems when others try to replicate your work using a different version of the software. (That is, one that doesn’t include the same peculiarities.)