You can watch them here on fanpop, just go to The Office (US) spot. Other good websites are:
www.tv-links.co.uk
www.alloftv.net
www.sidereel.com

I think if you want to watch for free, sidereel is the place to be. HA that rhymed!! Anyway, they have several links for each episodes, even some with Chinese subtitles. I got hooked post season three, and I got caught up there!