If you are not sure, which version of the operating system is installed on your machine, click on:

• (Vista:) Start → Computer → System Properties (right mouse tab) and check the information about the System type

• (Windows XP and 2003:) My Computer (right mouse tab) → Properties → General: The 64 bit versions have an entry there, which reads: “ .. x64 Edition” → Shortcut: Just click on the 'Windows-key' and 'Break' to get to System Properties

The command line tool systeminfo, which is included in XP and more recent versions of Windows, provides an exhaustive snapshot about important system parameter. Below is an example outout:

Microsoft Windows [Version 5.2.3790]
(C) Copyright 1985-2003 Microsoft Corp.

X:\temp>systeminfo

Host Name:                 XYZ
OS Name:                   Microsoft(R) Windows(R) Server 2003, Standard Edition

OS Version:                5.2.3790 Service Pack 2 Build 3790
OS Manufacturer:           Microsoft Corporation
OS Configuration:          Member Server
OS Build Type:             Uniprocessor Free
Registered Owner:          XYZ
Registered Organization:   GAMS Development Corp.
Product ID:                69712-XXX-YYYYYYY-ZZZ
Original Install Date:     7/6/2006, 12:44:48 PM
System Up Time:            N/A
System Manufacturer:       Microsoft Corporation
System Model:              Virtual Machine
System Type:               X86-based PC
Processor(s):              1 Processor(s) Installed.
                           [01]: x86 Family 15 Model 33 Stepping 2 AuthenticAMD~1994 Mhz
BIOS Version:              A M I  - 9000520
Windows Directory:         C:\WINDOWS
System Directory:          C:\WINDOWS\system32
Boot Device:               \Device\HarddiskVolume1
System Locale:             en-us;English (United States)
Input Locale:              en-us;English (United States)
Time Zone:                 (GMT-05:00) Eastern Time (US & Canada)
Total Physical Memory:     1,023 MB
Available Physical Memory: 700 MB
Page File: Max Size:       2,473 MB
Page File: Available:      2,202 MB
Page File: In Use:         271 MB
...