C#.NET windows应用程序怎样获得硬盘序列号

using System;
using System.Runtime.InteropServices;

namespace ArLi.CommonPrj {

#region how use this?
/*
string sVol = getvol.GetVolOf("C");
*/
#endregion

public class getvol{

[DllImport("kernel32.dll")]
private static extern int GetVolumeInformation(
string lpRootPathName,
string lpVolumeNameBuffer,
int nVolumeNameSize,
ref int lpVolumeSerialNumber,
int lpMaximumComponentLength,
int lpFileSystemFlags,
string lpFileSystemNameBuffer,
int nFileSystemNameSize
);

public static string GetVolOf(string drvID){
const int MAX_FILENAME_LEN = 256;
int retVal = 0;
int a =0;
int b =0;
string str1 = null;
string str2 = null;

int i = GetVolumeInformation(
drvID + @":\",
str1,
MAX_FILENAME_LEN,
ref retVal,
a,
b,
str2,
MAX_FI