Just so the VB.NET folks don't feel too left out...

Private Function IsPalindrome(ByVal TestString As String) As Boolean

Dim First As Integer = 0

Dim Last As Integer = TestString.Length - 1

While First < Last

   If TestString.Substring(First, 1) = TestString.Substring(Last, 1) Then

First += 1

Last -= 1

Else

Return False

End If

End While

Return True

End Function