From (
http://www.onlinecomputertips.com/hardware/hardware_req.html), and
http://windows.microsoft.com/systemrequirements
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
Windows Vista
All Editions (minimum requirements)
800 MHz processor and 512 MB of system memory
20 GB hard drive with at least 15 GB of available space
Support for Super VGA graphics
CD-ROM drive
Below are the recommended requirements from Microsoft for Vista but we recommend a faster processor like a Core2Duo and 2 GB of RAM for any version of Vista.
Home Basic
1 GHz 32-bit (x86) or 64-bit (x64) processor
512 MB of RAM
20 GB hard drive with at least 15 GB of available space
Support for DirectX 9 graphics and 32 MB of graphics memory
DVD-ROM drive
Home Premium / Business / Ultimate
1 GHz 32-bit (x86) or 64-bit (x64) processor
1 GB of RAM
40 GB hard drive with at least 15 GB of available space
DVD-ROM drive
Support for DirectX 9 graphics with:
* WDDM Driver
* 128 MB of graphics memory (minimum)
* Pixel Shader 2.0 in hardware
* 32 bits per pixel
Windows Server 2003
Web Edition
Supports two processors and 2GB of RAM.
133-MHz processor (550 MHz recommended)
128 MB of RAM (256 MB recommended; 2 GB maximum)
1.5 GB hard disk space
Standard Edition
Supports four processors and 4GB of RAM.
133-MHz processor required; 550-MHz or faster processor
128 MB of RAM required; 256 MB or more recommended
1.5 GB hard disk space
Enterprise Edition
Supports eight processors and 32GB of RAM.
133-MHz or faster processor for x86-based PCs; 733-MHz for Itanium-based PCs
128 MB of RAM required; 256 MB or more recommended
1.5 GB hard disk space
Datacenter 32-Bit Edition
Supports 32 processors and 64GB of RAM.
400 MHz processor required; 733 MHz processor recommended
Minimum: 512 MB of RAM; recommended: 1 GB of RAM
1.5 GB hard disk space
Datacenter 64-Bit edition
Supports 64 processors and 512GB of RAM.
Minimum: 400 MHz processor for x86-based computers or 733 MHz for Itanium-based computers; recommended: 733 MHz processor
Minimum: 512 MB of RAM; recommended: 1 GB of RAM
1.5 GB hard disk space
Windows2000
Windows 2000 Professional
Supports up to two processors and up to 4GB of RAM.
Pentium 133 MHz, 65MB of RAM, 650 MB free hard disk space (2 G recommended)
Windows 2000 Server
Supports up to four processors and up to 4GB of RAM.
Pentium 133 MHz, 128MB of RAM, 1 GB free hard disk space (2 G recommended)
Windows 2000 Advanced Server
Supports up to eight processors and up to 8GB of RAM
Pentium 133 MHz, 256MB of RAM, 1 GB free hard disk space (2 G recommended)
Windows 2000 Datacenter Server
Supports up to 32 processors and up to 64GB of RAM.
Pentium 133 MHz, 256MB of RAM, 1 GB free hard disk space (2 G recommended)
Windows XP
Home
Supports 1 processor and up to 4GB of RAM
233 MHz CPU (300 MHz recommended)
64 MB of RAM (128 recommended)
1.5 GB of available hard disk space
Professional
Supports up to 2 processors and up to 4GB of RAM
233 MHz CPU (300 MHz recommended)
64 MB of RAM (128 recommended)
1.5 GB of available hard disk space
64 Bit Edition
Supports up to 2 processors and up to 64GB of RAM
AMD Athlon 64, AMD Opteron, Intel Xeon with Intel EM64T support, Intel Pentium 4 with Intel EM64T support CPUs
256 MB of RAM
1.5 GB of available hard disk space
Windows 95/98/ME
Windows 95
Supports 1 processor and up to 2GB of RAM
x386 CPU
4 MB of RAM (8 recommended)
55 MB of available hard disk space
Windows 98
Supports 1 processor and up to 2GB of RAM
66 MHz CPU (300 MHz recommended)
16 MB of RAM (24 recommended)
225 MB of available hard disk space
Windows ME
Supports 1 processor and up to 2GB of RAM
150 MHz CPU (300 MHz recommended)
32 MB of RAM (64 recommended)
320 MB of available hard disk space