Deleting file throws file in use exception

Question

I have a file upload control that allows users to upload an image file. Rather then forcing them to use a specific size image, I am trying to resize it, save it the resized version to a folder and then delete the original.

When I try to delete the file, I keep getting "file in use" exception. I have searched and tried all suggestions to no avail.

This is the latest try, at which point I decided to seek help. I pass the source path (where original file is in, a destination path where resized file is to end up in, file name and width to which it should be resized, keeping aspect ratio):

public static void CreateResizedCopy(String sourcePath, String destinationPath, String filename, int width)
{
    if (!File.Exists(destinationPath + filename))
    {
        System.Drawing.Image image = System.Drawing.Image.FromFile(sourcePath + filename);
        float AspectRatio = (float)image.Size.Width / (float)image.Size.Height;
        int newHeight = Convert.ToInt32(width / AspectRatio);
        Bitmap thumbnailBitmap = new Bitmap(width, newHeight);
        Graphics thumbnailGraph = Graphics.FromImage(thumbnailBitmap);
        thumbnailGraph.CompositingQuality = CompositingQuality.HighQuality;
        thumbnailGraph.SmoothingMode = SmoothingMode.HighQuality;
        thumbnailGraph.InterpolationMode = InterpolationMode.HighQualityBicubic;
        var imageRectangle = new Rectangle(0, 0, width, newHeight);
        thumbnailGraph.DrawImage(image, imageRectangle);
        thumbnailBitmap.Save(destinationPath + filename, ImageFormat.Jpeg);
        thumbnailGraph.Dispose();
        thumbnailBitmap.Dispose();
        image.Dispose();

        System.GC.Collect();
        System.GC.WaitForPendingFinalizers();

        if (!FileInUse(sourcePath + filename))
        {
            File.Delete(sourcePath + filename);
        }
        else
        {
            // Error here: file is in use
            using (FileStream fs = new FileStream(sourcePath + filename, FileMode.OpenOrCreate))
                fs.Dispose();
        }
    }
}

public static bool FileInUse(string path)
{
    try
    {
        using (FileStream fs = new FileStream(path, FileMode.OpenOrCreate))
        {
            return false;
        }
    }
    catch (IOException ex)
    {
        return true;
    }
}

UPDATE This is the AJAX AsynFileUpload's upload completed event handler. It saves the file to a "Resize" folder. If image needs to be resized, it calls the method to resize it and then moves it to its final resting place. If not, no resizing is done, it just moves the file. It then "attempts" to delete the file in resize folder and it chokes!

protected void fuNewsImage_UploadedComplete_Resize(object sender, AsyncFileUploadEventArgs e)
{
    if (fuNewsImage.HasFile)
    {
        HttpPostedFile file = fuNewsImage.PostedFile;
        string sFileName = fuNewsImage.FileName;
        string sFileSize = e.FileSize;

        string sSaveFolder = ImageFilePath.TEMP_FOLDER_EA_TEST + "\\";
        string sResizeFolder = ImageFilePath.TEMP_FOLDER_EA_TEST + "\\Resized\\";

        fuNewsImage.SaveAs(Server.MapPath(sResizeFolder + sFileName));
        System.Drawing.Image img = System.Drawing.Image.FromFile(Server.MapPath(sResizeFolder) + sFileName);
        int iImgWidth = img.Width;
        int iImgHeight = img.Height;

        if (iImgWidth > ImageInfo.MAX_WIDTH)
        {
            // sSaveFolder is the efinal resting place of the uploaded image
            // If image width is more than max allowed, resize it, save it in sSaveFolder
            Utils.CreateResizedCopy(Server.MapPath(sResizeFolder), Server.MapPath(sSaveFolder), sFileName, 600);

            System.Threading.Thread.Sleep(1000);
            File.Delete(Server.MapPath(sSaveFolder + sFileName));
        }
        else  // just move it t sSaveFolder
        {
            File.Move(Server.MapPath(sResizeFolder) + sFileName, Server.MapPath(sSaveFolder) + sFileName);
        }
        //        ---  Chokes here  ---
        Array.ForEach(Directory.GetFiles(Server.MapPath(sResizeFolder)), File.Delete);
    }
}