最受欢迎的GroupBy和Linq to实体

我有一个带有包含产品的invoiceline表的标准存储模式。我想得到一份按销售额排列的前五名产品的清单。最干净的方法是什么?这不是最好的方法:

    private List<Product> GetTopProducts(int count)
    {
        var topProducts = from invoiceLine in storeDB.InvoiceLines
                        group invoiceLine by invoiceLine.ProductId into grouping
                        orderby grouping.Count() descending
                        select new 
                        {
                            Products = from Product in storeDB.Products 
                            where grouping.Key == Product.ProductId
                            select Product
                        };
        return topProducts.AsEnumerable().Cast<Product>().Take(count).ToList<Product>();
    }