using System;

using System.Linq;

using System.Collections;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var lst=new List<Item>{ 

            new Item {ComputerName="Comp1",UsedVolume=1,FreeVolume=1, Date=DateTime.Now.Date.AddMinutes(5)},

            new Item {ComputerName="Comp1",UsedVolume=2,FreeVolume=1, Date=DateTime.Now.Date.AddMinutes(15)},

            new Item {ComputerName="Comp2",UsedVolume=3,FreeVolume=1, Date=DateTime.Now.Date.AddMinutes(5)},

            new Item {ComputerName="Comp2",UsedVolume=0,FreeVolume=1, Date=DateTime.Now.Date.AddMinutes(10)},

            new Item {ComputerName="Comp1",UsedVolume=1,FreeVolume=1, Date=DateTime.Now.Date.AddMinutes(5)}

        };

​

        var finalSub= lst.OrderByDescending(x=>x.Date).ThenBy(x=>x.UsedVolume)

            .Select(x=>new{ComputerName=x.ComputerName,UsedVolume=x.UsedVolume,FreeVolume=x.FreeVolume,Date=x.Date})

            .GroupBy(g=> new {ComputerName=g.ComputerName}).Select(x=>new Item{ComputerName=x.Key.ComputerName,UsedVolume=x.Max(y=>y.UsedVolume),FreeVolume=x.Where(y=>y.UsedVolume==(x.Max(z=>z.UsedVolume))).First().FreeVolume});

        foreach(var res in finalSub)

        {

            Console.WriteLine("{0} - {1} - {2}", res.ComputerName, res.UsedVolume,res.FreeVolume);

        }

    }

    public class Item

    {               

        public string ComputerName { get; set; }

        public double UsedVolume { get; set; }

        public double FreeVolume { get; set; }

        public DateTime Date {get;set;}

    }

}