Will Microsoft win anything if all their laptop user move into tablet but just use the tablet the same way as their old laptop?
Yeah, because they bought MS stuff.
The biggest thing you've got to understand is that it isn't quite a traditional laptop. It's an attempt to be the best of both worlds. You can use it like a laptop if you want. Lay it out on your desk, grab a mouse, and start typing away on the (apparently pretty good) thin keyboard thing. Or if you want to, you can flip the keyboard around back, pick it up, and start using more touch friendly apps.
...or even better, you can grab a stylus, and start doodling in Photoshop on the thing.
It's not a tablet as Apple envisioned it. It's not a supplemental item to a much more powerful machine. It's a powerful machine in its own right, and has the potential to be far more capable and flexible than the iPad.
Problem is, adding more capability and flexibility makes it that much less easier to just pick up and use right away. Even the RT, the more consumer oriented rev, isn't quite as straightfoward as the iPad. It's for this reason I don't think it'll be nearly as popular in the mom 'n pop sector. The iPad is more than good enough for them as is. It's practically designed for them. But for the enthusiast, the hobbyist, and the professional? There's really no competition.
One good thing, though. If the Surface does succeed, I'm sure it'll hurry Apple along to release their eventual and inevitable iPad/MBA hybrid.