Get pc (system) information on windows machine

WMI is what you're looking for.

http://www.codeproject.com/KB/cs/EverythingInWmi02.aspx

Let me add the link to Part 3 too, which concentrates on hardware via WMI

http://www.codeproject.com/KB/cs/EverythingInWmi03.aspx

MSDN is also a great resource for WMI scopes...

http://msdn.microsoft.com/en-us/library/aa394554(v=vs.85).aspx

There is a nuget package called MissingLinq.Linq2Management that has wrapped pretty much everything about WMI into a nice strongly typed object. Seems pretty nice.

https://missinglinq.codeplex.com/

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Management;   //This namespace is used to work with WMI classes. For using this namespace add reference of System.Management.dll .
using Microsoft.Win32;     //This namespace is used to work with Registry editor.

namespace OperatingSystemInfo1
{
    class TestProgram
    {
        static void Main(string[] args)
        {
            SystemInfo si = new SystemInfo();       //Create an object of SystemInfo class.
            si.getOperatingSystemInfo();            //Call get operating system info method which will display operating system information.
            si.getProcessorInfo();                  //Call get  processor info method which will display processor info.
            Console.ReadLine();                     //Wait for user to accept input key.
        }
    }
    public class SystemInfo
    {
        public void getOperatingSystemInfo()
        {
            Console.WriteLine("Displaying operating system info....\n");
            //Create an object of ManagementObjectSearcher class and pass query as parameter.
            ManagementObjectSearcher mos = new ManagementObjectSearcher("select * from Win32_OperatingSystem");
            foreach (ManagementObject managementObject in mos.Get())
            {
                if (managementObject["Caption"] != null)
                {
                    Console.WriteLine("Operating System Name  :  " + managementObject["Caption"].ToString());   //Display operating system caption
                }
                if (managementObject["OSArchitecture"] != null)
                {
                    Console.WriteLine("Operating System Architecture  :  " + managementObject["OSArchitecture"].ToString());   //Display operating system architecture.
                }
                if (managementObject["CSDVersion"] != null)
                {
                    Console.WriteLine("Operating System Service Pack   :  " + managementObject["CSDVersion"].ToString());     //Display operating system version.
                }
            }
        }

        public void getProcessorInfo()
        {
            Console.WriteLine("\n\nDisplaying Processor Name....");
            RegistryKey processor_name = Registry.LocalMachine.OpenSubKey(@"Hardware\Description\System\CentralProcessor\0", RegistryKeyPermissionCheck.ReadSubTree);   //This registry entry contains entry for processor info.

            if (processor_name != null)
            {
                if (processor_name.GetValue("ProcessorNameString") != null)
                {
                    Console.WriteLine(processor_name.GetValue("ProcessorNameString"));   //Display processor ingo.
                }
            }
        }
    }
}

You have PC Name as a value you want, so you can get this from Environment.MachineName if you want the local computer, or you can do IPHostEntry hostEntry = Dns.GetHostEntry(ip); then string host = hostEntry.HostName; to use DNS to resolve a remote computer's name if you only have its IP.

You can get certain information from the registry, after you check that Remote Registry is running, assuming you want a remote computer:

ServiceController sc = new ServiceController("RemoteRegistry", computer); 
if (sc.Status.Equals(ServiceControllerStatus.Running)) 
{ 
    // do your stuff 
} 

And you can start it if found stopped:

if (sc.Status.Equals(ServiceControllerStatus.Stopped) || 
sc.Status.Equals(ServiceControllerStatus.StopPending)) 
{ 
    sc.Start(); 
} 

Add this using statement to the top of your page:

using Microsoft.Win32;

For the Computer name, you can go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\ComputerName\ActiveComputerName:

string path = @"HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\ComputerName\ActiveComputerName";
RegistryKey rk = RegistryKey.OpenRemoteBaseKey(RegistryHive.LocalMachine, computer).OpenSubKey(path);
string pcName = rk.GetValue("computerName").ToString();

For any local registry commands, just remove RegistryKey.OpenRemoteBaseKey( and , computer) - it becomes:

RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry64).OpenSubKey(path);

The RegistryView.Registry64 is usually not required (you can use RegistryView.Default instead), but can be necessary if building a 32-bit app that needs to reach into a registry on a 64-bit OS. Instead of all in one line, you could also do something like this, for example:

using (var root = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry64))
{
    using (var key = root.OpenSubKey(@"Software\Microsoft\Windows NT\CurrentVersion", false))
    {
        var registeredOwner = key.GetValue("RegisteredOwner");
    }
}

Credit: https://social.msdn.microsoft.com/Forums/en-US/ea997421-4d55-49db-97ad-cf629c65577b/registrylocalmachineopensubkey-does-not-return-all-values?forum=csharpgeneral

For the CPU name:

string path = @"HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\0";
RegistryKey rk = RegistryKey.OpenRemoteBaseKey(RegistryHive.LocalMachine, computer).OpenSubKey(path);
string cpuName = rk.GetValue("processorNameString").ToString();

For the OS Name and key:

string path = @"SOFTWARE\Microsoft\Windows NT\CurrentVersion";
RegistryKey rk = RegistryKey.OpenRemoteBaseKey(RegistryHive.LocalMachine, computer).OpenSubKey(path);
string osName = rk.GetValue("productName").ToString();
string servicePack = rk.GetValue("CSDVersion").ToString();
byte[] digitalProductId = registry.GetValue("DigitalProductId") as byte[];
string osProductKey = DecodeProductKey(digitalProductId);

From Geeks With Blogs for getting product keys:

public static string DecodeProductKey(byte[] digitalProductId)
{
  // Offset of first byte of encoded product key in 
  //  'DigitalProductIdxxx" REG_BINARY value. Offset = 34H.
  const int keyStartIndex = 52;
  // Offset of last byte of encoded product key in 
  //  'DigitalProductIdxxx" REG_BINARY value. Offset = 43H.
  const int keyEndIndex = keyStartIndex + 15;
  // Possible alpha-numeric characters in product key.
  char[] digits = new char[]
  {
    'B', 'C', 'D', 'F', 'G', 'H', 'J', 'K', 'M', 'P', 'Q', 'R', 
    'T', 'V', 'W', 'X', 'Y', '2', '3', '4', '6', '7', '8', '9',
  };
  // Length of decoded product key
  const int decodeLength = 29;
  // Length of decoded product key in byte-form.
  // Each byte represents 2 chars.
  const int decodeStringLength = 15;
  // Array of containing the decoded product key.
  char[] decodedChars = new char[decodeLength];
  // Extract byte 52 to 67 inclusive.
  ArrayList hexPid = new ArrayList();
  for (int i = keyStartIndex; i <= keyEndIndex; i++)
  {
    hexPid.Add(digitalProductId[i]);
  }
  for (int i = decodeLength - 1; i >= 0; i--)
  {
    // Every sixth char is a separator.
    if ((i + 1) % 6 == 0)
    {
      decodedChars[i] = '-';
    }
    else
    {
      // Do the actual decoding.
      int digitMapIndex = 0;
      for (int j = decodeStringLength - 1; j >= 0; j--)
      {
        int byteValue = (digitMapIndex << 8) | (byte)hexPid[j];
        hexPid[j] = (byte)(byteValue / 24);
        digitMapIndex = byteValue % 24;
        decodedChars[i] = digits[digitMapIndex];
      }
    }
  }
  return new string(decodedChars);
}

That gets the hard ones out of the way. Point is, the registry is your friend.