To run Windows 7 flawlessly, your PC must meet the system requirements.

Windows 7 requires:

• 1 gigahertz (GHz) or faster 32-bit (x86) or 64-bit (x64) processor
• 1 gigabyte (GB) RAM (32-bit) or 2 GB RAM (64-bit)
• 16 GB available hard disk space (32-bit) or 20 GB (64-bit)
• DirectX 9 graphics device with WDDM 1.0 or higher driver

Additional requirements:

• Internet access (fees may apply)
• Depending on resolution, video playback may require additional memory and advanced graphics hardware
• For some Windows Media Center functionality a TV tuner and additional hardware may be required
• Windows Touch and Tablet PCs require specific hardware
• HomeGroup requires a network and PCs running Windows 7
• DVD/CD authoring requires a compatible optical drive
• BitLocker requires Trusted Platform Module (TPM) 1.2
• BitLocker To Go requires a USB flash drive
• Windows XP Mode requires an additional 1 GB of RAM, an additional 15 GB of available hard disk space, and a processor capable of hardware virtualization with Intel VT or AMD-V turned on
• Music and sound require audio output

Applies To:

• Windows 7 Ultimate
• Windows 7 Professional
• Windows 7 Home Premium
• Windows 7 Home Basic
• Windows 7 Starter

Courtesy: Microsoft