As I've said, I bought my machine from Sam's Technology (or something very similar) on the top floor in Mongkok - they've got a little component place on one side, and a larger monitor shop directly opposite. Their prices may not be the absolutely lowest, but they have a decent range, decent stock, and the guys seem friendly, helpful, speak some English, and are willing to discuss options (what if I get this motherboard and that CPU - or that motherboard and this CPU, etc.). They're not that interested in doing deals - they'll shave a bit off to round a total down, or throw in something cheap like a keyboard or case, maybe - but they seem pretty reasonable anyway...