Canadians teaching in Korea wanting to stop in Bejing for 5 days of transit on way back home ?Visa?

Someone please help ASAP!!!

We are two Canadians who are currently teaching English in Korea. Our contract expires on Oct. 31st, 2012, and our ARC cards expire on November 26th, 2012. Our flights back home are already booked by our school. We are flying out to Beijing on November 2nd, and then we have a flight from Beijing to Vancouver, Canada booked on November 7th, 2012. Do we still need our ARC cards to expire 6 months later if we are applying for a transit visa and not a tourist visa? Someone please help, we are really stressing out about this... If we are not going back to Korea, why would we need an ARC card that expires at least 6 months after our entry to China?

Thanks!