ASP.Net, SQL, Using Datetime Objects As Variables (keeps Throwing Error)

Sorry seem to be havign no end of trouble with SQL today.
 I need to create a query that will rank tickets using the row count of another table which has a relationship with the primarykey of that ticket table. I decided to spilt it into two querys, one which gets the count each ticketid has within a date peroid and relating to a os::
 SELECT     COUNT(*) AS count, Tickets.TicketID, Systems.OS
FROM         Rating INNER JOIN
                      Tickets ON Rating.TicketID = Tickets.TicketID INNER JOIN
                      Systems ON Tickets.SystemID = Systems.SystemID
WHERE     (Rating.DateVoted >= @date)
GROUP BY Tickets.TicketID, Systems.OS
HAVING      (Systems.OS = @osid)
 
This works, BUT when I put in the date using:
 
command.CommandText = "SELECT COUNT(*) AS count, Tickets.TicketID, Systems.OS FROM Rating INNER JOIN Tickets ON Rating.TicketID = Tickets.TicketID INNER JOIN Systems ON Tickets.SystemID = Systems.SystemID WHERE (Rating.DateVoted >=" + Datetime.Now.Adddays(-7) + ") GROUP BY Tickets.TicketID, Systems.OS HAVING (Systems.OS =" + 1 + ")";
 
And it throws up an error saying there was a syntax error at '22' (the hour I am currently on).
 
So:
 Any idea how I can fix thisAny ideas on creating a query that will do the above, but also return the ticket informationHow do you link querys (I might have to do this if I can't work out 2)Please, If anyone has any ideas. This is driving me crazy