MVC3 & EF4 How to pass data to a select list using a viewmodel

I have viewmodel which i am contructing in a Create get action,

public class SiteAdminCreateViewModel
{
    public int CustomerId { get; set; }
    public string ContactName { get; set; }
    [Required(ErrorMessage = "A contact number is Required")]
    public string ContactNo { get; set; }
    public IEnumerable<SelectListItem> CustomerNames { get; set; }
}

public ViewResult Create(SiteAdminCreateViewModel model) 
    {
        var query = from cs in repository.CustomerSites
                    select new SiteAdminCreateViewModel
                    {
                        CustomerId = cs.Customer.CustomerId,
                        ContactName = cs.ContactName,
                        ContactNo = cs.ContactNo,
                        CustomerNames = ??

                    };
        return View(query.ToList());            
    }

In the viewmodel i have a select list defined as CustomerNames, i want to be able to use that select list to insert the CustomerId value (also defined in the viewmodel) taken from the Customers table which is a seperate but related entity,

Can anyone please help with how i can set the selec开发者_JAVA技巧t list up in the controller to receive a list of CustomerNames from the Customer entity?

Also my view throws an exception when i change its declaration to accept the viewmodel,

The model item passed into the dictionary is of type  'System.Data.Entity.Infrastructure.DbQuery`1[CustomerOrders.WebUI.Models.SiteAdminCreateViewModel]', but this dictionary requires a model item of type 'CustomerOrders.WebUI.Models.SiteAdminCreateViewModel'.

Any help/advice is appreciated.

public ActionResult MyController(SiteAdminCreateViewModel model)
{
 var query = from cs in repository.CustomerSites
                select new SiteAdminCreateViewModel
                {
                    Value= cs.Customer.CustomerId,
                    Text= cs.ContactName
                };
    ViewBag.CustomerNames=query.ToList();
    return View(model);
}

inside view

@Html.DropDownListFor("CustomerNames")