How much RAM is needed to run Windows 7?
From personal experience with Windows XP machines and a Vista machine running 512 mb RAM, 2 GB should be the minimum for a useful Windows 7 machine.
With the Vista machine, it only "needed" 512 mb to run, but increasing the memory to 2 gb made it a lot more user friendly.
As you can see from the other answers, "needed" is not an accurate figure. Microsoft state that 1GB is the minimum required, but for a machine to be usable you really need 2GB, and more memory will improve performance upt to about 3GB.
Beyond that it makes no difference to the 32 bit version of Windows (which can only "see" around 3.2GB), and most people won't need more than 3GB anyway. However, if you have the 64 bit version, you can use more memory and it can be useful for specific reasons - running virtual machines, doing heavy duty Photoshop or Premiere work, and running a minority of games.
Besides the minimum requirements,if you want Windows 7 to run optimally,then use 2 GB RAM for 32-bit and 4 GB RAM for 64-bit versions.
For 32 bit Windows 7, 1GB is minimum for any usable performance, but the higher the better. 2GB minimum is recommended to get decent enough performance. If you use only 1GB, then disabling Windows Aero and other flashy visual features would be recommended.
Windows 7 64 bit needs a minimum of 2GB, but 3GB or more is highly recommended for decent performance. For 2GB of memory, I would recommend disabling Aero and other flashy visual features.
The requirements are a minimum of 1GB for 32-bit and 2GB for 64-bit installations.
My personal suggestion is at least 2GB for either, better 4GB.
Windows 7 system requirements
If you want to run Windows 7 on your PC, here's what it takes:
• 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