canadacomputers.com has the best stuff for computers in canada that isn't used, but doesn't ship. Tigerdirect is ok, but don't do their rebates. NCIX is good, I've heard, and anitec is good too (in terms of PM, but shipping is awful.
For high end stuff, nothing, nothing beats genitechcomputers.com. Run by a friend of mine, see if you can find lower prices.