BenQ used to be Acer and I'm not sure who Microtech is. This kind of info is usually pretty tough to find.
For instance, do a search and see if you can find out who makes HP, Dell, Compaq, Toshiba and Gateway notebooks. Or try this, see who makes Dell LCD's or Plasma tv's. Even better than that, search for who makes the panel that is used in those LCD's.
Ok, the notebook answer would be either Quanta, Compal or Uniwill. There's a couple of other manufacturers out there but there's only a handful of companies that actually manufacture notebooks. There are a couple of reasons that this information is not easy to find. First, when Dell or Gateway brands a notebook as a "Dell" or "Gateway" they are the company who supports the product. Yes, if your notebook is toast, they will probably end up sending it back to Compal or Quanta but you do not have that option. Unlikes hard drives (retail box or OEM that aren't gray market) which you can send back to the manufacturer, you cannot contact Quanta or Compal and RMA your defective notebook.
Since this is the case, there really is no reason for end users to know who manufactures the barebone unit. Basically, Dell buys barebone units from the manufacturer, adds a CPU, RAM, HDD, FDD, CD, etc., assembles it, installs the OS and sells it with a Dell sticker.