Good points by coan. If you say though, Binabik, that you hate sitting at a desk, than a laptop will be a better choice. But just keep in mind, that, as coan said, you will pay more for the same abilities computation wise. Plus, it is a lot cheaper and easier to later upgrade a desktop than it is to upgrade a laptop. So it boils down to how much you prefer the flexibility of sitting on your couch with the laptop over better prices.

I would say out of the four brands you mentioned Sony is the one that is the most overpriced. I have a thing for Dell myself. But coan's right, as long as you stay with a big name, you will have a good chance of being very satisfied, and always a small chance not to be.