var ordersWithCustomersFromXml =
from c in xmlCustomers.Elements("customer")
join o in orders
on (String)c.Element("name") equals o.Name
orderby (String)c.Element("name")
select new {
Name = (String)c.Element("name"),
City = (String)c.Attribute("city"),
IdProduct = o.IdProduct,
Quantity = o.Quantity };
