java -Xmx1024M -Xms1024M -jar minecraft_server.jar nogui

// find all java processes running Minecraft servers
var query =
    "SELECT ProcessId "
    + "FROM Win32_Process "
    + "WHERE Name = 'java.exe' "
    + "AND CommandLine LIKE '%minecraft_server%'";

// get associated processes
List<Process> servers = null;
using (var results = new ManagementObjectSearcher(query).Get())
    servers = results.Cast<ManagementObject>()
                     .Select(mo => Process.GetProcessById((int)(uint)mo["ProcessId"]))
                     .ToList();