--Table structure
CREATE TABLE dbo.GUIDTable
(
GUIDCol uniqueidentifier NOT NULL PRIMARY KEY,
OtherColumn varchar(25) NOT NULL

)
GO

--Stored procedure for inserting rows
CREATE PROCEDURE dbo.InsertGUIDs
(
@OtherColumn varchar(25)
)
AS
BEGIN
SET NOCOUNT ON

DECLARE @GUIDCol uniqueidentifier

SET @GUIDCol = NEWID() --Creating the new GUID value before hand

INSERT INTO dbo.GUIDTable (GUIDCol, OtherColumn) VALUES (@GUIDCol, @OtherColumn)

IF @@ERROR = 0 AND @@ROWCOUNT = 1
BEGIN
/* This GUID will be returned to the client as a recordset */
SELECT @GUIDCol AS '@@GUID'
RETURN 0
END
ELSE
BEGIN
RAISERROR('Something went wrong :-(', 16, 1)
RETURN -1
END
END
GO