While it's recommended that you run Windows 8 on modern hardware, the new operating system will run on older computers, as long as they feature the following specifications (as per Microsoft's recommendation).
CPU: 1GHz or faster
Memory: 1GB of RAM (for the 32-bit version) or 2GB RAM (for the 64-bit version)
Storage space: 16GB (for the 32-bit version ) or 20GB (for the 64-bit version)
Graphics: a graphics adapter that supports Direct X 9 with Windows Display Driver Model (WDDM) 1.0 or higher
The screen resolution for new-style Windows 8 apps needs to be a minimum of 1024x768, and in order for a system to support the Snap feature for new-style apps, the resolution needs to be 1366x768.
If you will be making use of BitLocker encryption, then it is recommended that your computer have a built-in Trusted Platform Module. If you want to use Secure Boot, which is a feature that provides security against malicious software during the boot up process, then you will need a computer that has a UEFI BIOS.
Proudly sponsored by Trend Micro