TigerDirect is easy, fast and good with warranty (make sure you hold onto your original packaging just incase). I deal with TD.ca personally and with my company when making I.T. Purchases.
TigerDirect, as well as NCIX are primary suppliers for many other retailers. In Canada there are only a small handful of companies that provide computer parts - NCIX, TD, CDW and i think there's one more.
If you're in Toronto - there are several TigerDirect Stores (Markham, Scarborough - and one more elsewhere, check the website).
Same deals at the store as online, sometimes even better at the store. I'm still trying to get up there to browse through the isles!