I have used Vonage for a few years now and am impressed with its reliability and quality. Just the other day I signed up for Skype, which is more flexible and much cheaper than the other VoIP options. I don't know if Vonage is available in Canada or not, but I recommend it as a land-line alternative. As for Skype, I've tried a few calls. The quality is very good and as I mentioned, you have a few options on how you use it - either attached to your computer or via a wireless connection to your home network. Assuming you already have a router at home, Skype is very easy to set up and I am almost certain that it is available in Canada.
For less than 100 USD a year, Skype gives you pre-paid telephone line with unlimited calling to the US and Canada - a remarkable savings over traditional service.
As someone else mentioned, one downside is the lack of 911 support. While some companies offer some kind of alternative, Skype has none. The other disadvantage is that if you lose power or your Internet connection at home, you won't be able to use your phone until those services are restored.
Cell phones help balance out those negatives however. If your cell carrier has local 911 service, then you're good to go!