You can use this:
var lines = File.ReadLines(ofd.FileName);
foreach (string line in lines.Skip(8))
Trace.WriteLine(line);
Because the File.ReadLines returns an IEnumerable<string>, the lines are only loaded when iterated.
Also check File.ReadLines Method http://msdn.microsoft.com/en-us/library/dd383503.aspx
Happy coding Hours ;_)