It's always best to update your operating system if possible. But here are our requirements:
Windows XP, Vista, 7* or later, Mac OS X 10.6 or later, or Linux: RHEL 5.6 or later, openSUSE 11.3 or later, or Ubuntu 10.04 or later.
Here is our system check. This test will tell you if you're ok or need some updating.
*Windows 7 is no longer being updated by Microsoft. It's best to update your operating system to the newest version if possible.