LINQ 2 SQL Group By Query... stuck on this.

[Nightcrawler]

I have the following tables that I have dragged into a .dbml file
(have only included the keys for simplicity).

CREATE TABLE [dbo].[Catalog](
[CatalogId] [int] NOT NULL)
CREATE TABLE [dbo].[CatalogFavorite](
[UserId] [uniqueidentifier] NOT NULL,
[CatalogId] [int] NOT NULL)

A user can add catalog items to their favorites. A user can also
browse other users favorites.

I am trying to write a LINQ to SQL query where I am seeing another
users favorites but I would also like to see if I have any of those
favorites in my own favorites. In SQL I would run this to get my
result:

SELECT Catalog.CatalogId, SUM(CASE WHEN
CatalogFavorite_1.UserId =
'my uniqueidentifier' THEN 1 ELSE 0 END) AS HasFavorite
FROM CatalogFavorite INNER JOIN
Catalog ON CatalogFavorite.CatalogId =
Catalog.CatalogId INNER JOIN
CatalogFavorite AS CatalogFavorite_1 ON
Catalog.CatalogId =
CatalogFavorite_1.CatalogId
WHERE (CatalogFavorite.UserId = 'uniqueidentifier of the
user I am
viewing')
GROUP BY Catalog.CatalogId

Can anyone help me doing this in LINQ? ANy help would be highly
appreciated.

Thanks in advance!