BJ, Haliburton, Slumberger and Big Eagle are probably all hiring.
The websites might only list american jobs, but i can pretty much garuntee that the canadian divisions are looking as well. Try phoning them. They all have offices in Red Deer, Calgary and Edmonton, as well as probably whitecourt, Grande Prairie, FSJ, Rocky, Edson etc.
Also check out:
http://www.oilfieldworkers.com/

I work on the producing side, so my company doesn't hire truckers. But just tell me the town you want to live in and I can scan in a list of service companies that operate out of there and email it to you.
PM me your email address.
Do you have any of your oilfield tickets? (H2S, TDG, First Aid etc?) Sometime it helps to have those before you apply, sometimes the company will pay for them for you when you are hired.

Also, do you have your heart set of driving truck? There are many jobs availible for someone with the desire to learn and some kind of farming or industrial experience.