List index in C#

[C# Programming]

Hi
I want to list folders,subfolders and files from all drives in a system.I tried a code which works well for C:\.I want the same for the other drives.I have listed the drives in listbox.Please give your suggestions.private void PaintList(String sss)
{

try
{
reader = new XmlTextReader("path.xml");

while (reader.Read())
{
switch (reader.NodeType)
{
case XmlNodeType.Text: //Display the text in each element.
// Console.WriteLine(reader.Value);
String s1;
s1 = reader.Value;
String ss;
ss = listBox1.SelectedItem.ToString();
sss = ss + s1;
object o3 = (object)sss;

DirectoryInfo dire = new DirectoryInfo(sss);

//DirectoryInfo[] dirs = dire.GetDirectories();

if (dire.Exists)
{
String[] folder;
folder = Directory.GetDirectories(sss);
foreach (string foldername in folder)
{
DirectoryInfo di = new DirectoryInfo(foldername);
if (di.Exists)
{
String[] files;
files = Directory.GetFiles(foldername, "*.exe*");

//FileInfo[] fi = dire.GetFiles();

foreach (String filename in files)
{
lvi = new ListViewItem();
lvi.Text = filename;
listView1.Items.Add(lvi);

lvsi = new ListViewItem.ListViewSubItem();
lvsi.Text = filename.Length.ToString();
lvi.SubItems.Add(lvsi);
//listView1.Items[0].SubItems.Insert(1, lvsi);


}



this.Controls.Add(listView1);
}
}
}
break;
}
}
}
catch (System.Exception err)
{
MessageBox.Show("Error: " + err.Message);
}

}