Since Windows Live Mail 2012 requires at least Windows Vista, any PC that supports or came pre-installed with it is likely good enough to support Microsoft's free email program. The bottom line: if your computer is relatively recent, you'll have no problems running Windows Live Mail (or any other Windows Live apps for that matter). Fine prints for Windows 8: you need Windows 8 professional, because Windows 8 "RT" doesn't support traditional desktop applications.
Note: since this site covers only the latest versions of Windows Live Mail (2012 and later), we ignore the system requirements for Windows XP. If you are running XP, please see our "Windows Live Mail for XP" tutorial.
Operating System - to get Windows Live Mail 2012, you need to run Windows Vista, Windows 7, or Windows 8 / 8.1. Below are the system requirements for Windows Live Mail only. Some other Windows Live apps require different software or hardware.
Memory (RAM) - you need at least 512 megabytes of RAM (total RAM, not "available RAM"). Since most computers have come with at least 2 gigabytes (2,000 megabytes) of memory for the past few years, this is probably a system requirement you won't have to worry about! Tip: How much RAM (memory) do I have?
Processor (CPU) - by and large, the processor determines how fast your computer is. Since Windows Live Mail isn't a particularly demanding application, it does fine with a single gigahertz of clock speed. Tip: What is my processor / CPU speed?
Screen Resolution - if you are currently using a screen resolution of less than 1024 by 768 pixels, you won't see the entire interface of Windows Live Mail. Beyond a few hidden commands (and not a lot of room to read your emails!), the program remains operational. Tip: change screen resolution in Vista or Windows 7 / 8
Graphics Card (GPU) - Windows Live Essentials apps require a graphics card or GPU that supports at least DirectX 9 and pixel shader model 2 or higher (which reasonably new ones do). Tip: What graphics card / GPU do I have?
Hard Drive Space - the amount of space Windows Live Mail and other programs take up on your disk will depend on the ones you choose to install. But all of them typically need less than 300 megabytes total. Exact file sizes are difficult to establish precisely, because unrelated libraries might need to be installed (like Microsoft's .NET framework). Tip: How much free space left on my hard drive?
Side info: other programs from the Windows Live suite, like Photo Gallery or Movie Maker have (modest) additional requirements. Neither is not necessary for Windows Live Mail (uncheck them when you download / install the suite).