Use the promo code MS4000 for the 4000 Microsoft Points and XBL12 for the 12-month XBOX Live Gold Membership.
The point cards are not for actually physical points cards, you will be emailed the codes that you will need to enter into your account on the XBOX website. These codes should be received within 1–5 minutes after your payment has cleared. These codes have been verified to work on Canadian accounts. It seems only the 1600 point cards do not work on Canadian accounts.
This site only accepts payments through PayPal, but you can of course still just use your credit card through PayPal and you are actually more secure that way.
Note: Before making a purchase your phone number will need to be verified. This is done through an automated system and it used to reduce fraud. It’s best to use a home phone number as people have been having issues with cell phones working for the process.