Jpeg Checker Function

Hi Folks,
I know I haven't yet put in the error checking functions, but apart from that do you see any method to improve this code?

Cheers,
Abhijit

VB Code:

Function CheckForJpegs(ByVal sFile As String) As Boolean
        'Author     -   Abhijit 
        'Date       -   19-July-2005
        'Purpose    -   Check if the given image file is a jpeg file or not.
        'Assumption -   The image file exists in the given location.
        Dim strFileStream As FileStream
        Dim binRead As BinaryReader
        Dim iByteCounter As Integer
        Dim strTemp As String
        iByteCounter = 0
 
        strFileStream = New FileStream(sFile, FileMode.Open)
        binRead = New BinaryReader(strFileStream)
        Dim fileByte() As Byte = binRead.ReadBytes(11)
            strFileStream.Close()
        For iByteCounter = 0 To 5
            strTemp = strTemp & Hex((fileByte(iByteCounter)))
        Next iByteCounter
 
        For iByteCounter = 6 To 10
            strTemp = strTemp & ChrW((fileByte(iByteCounter)))
        Next iByteCounter
 
 
 
        If InStr(strTemp, "JFIF", CompareMethod.Text) Then
            CheckForJpegs = True
        ElseIf strTemp.Substring(0, 5) = "FFD8FF" Then 'This test is required for files created on Mac / older versions on PC
            CheckForJpegs = True
        Else
            CheckForJpegs = False
        End If
    End Function