Using my Galaxy s2 as my laptop, with MHL and Bluetooth mouse and keyboard

I think you don't understand the whole idea of this.

Connecting your phone on a LCD and using a keyboard and a mouse don't make your phone a laptop.

You will still have to use android applications, so if you only used your laptop for email, music, movies and other casual stuff you'll be fine, but that still doesn't make it a laptop.


If something looks cool that doesn't make its practical.

You'll need to connect your phone with a charger during usage, because it will probably drain your battery very fast, and two things will probably happen:
- overheat and ruin your phone
- damage your battery



PS:

1. You can already set your phone's screen for horizontal ( ex: ADW Launcher can do that )
You can use a theme to make it look something similar to Windows.

2. Your phone's performance will be the same, you're not changing anything by using a keyboard and a LCD.