I have a condo in Calgary with a mortgage and a Canadian bank account. My condo is rented at arms length so no problems and I am still considered a non-resident.
I recommend talking to an accountant who does expat taxes if your concerned. It's not very expensive, a few hundred dollars, and if Revenue Canada determines when you return that you weren't a non-resident they'll bend you over. You'll have to pay back taxes+interest.
You'll have to file a '07 Canadian tax return anyway for the time you work in Canada until you leave, so you might as well file as a non-resident at the same time.