I'm Chinese, so I've been around to almost all of the Chinese computer stores in the GTA.
Try these locations (some may be repeated in previously posts):
Canada Computers at Pacific Mall or College/Spadina
Macrotech at Midland/Finch (the owner and I are pretty good friends, he will pricematch anything, and deduct 5%)
Infonec somewhere in Markham - pretty decent prices.
Sonnam somewhere downtown - pretty good prices on miscellaneous things most other stores don't sell.
PC Village at First Markham Place (Highway7 and Woodbine I think) - good prices overall.
Logic Computer House at Steeles/Woodbine - lowest price in Toronto I could find on Radeon 8500LEs ($171CDN!)
Promax at Times Square - probably the most knowledgable computer technicians in all of Toronto there - cool guys, good prices.
In terms of service - Macrotech and Promax are top notch. Eddie@Macrotech, and Nelson@Promax - just ask for them.