Second monitor for laptop

[Bullit]

I decided that i also need a second monitor to complement my laptop when i am working at home. It is a big productivity benefit doing a tutorial or everything else that i need more screen size.

I have 17" 1920x1080 laptop, what advice i should follow buying? I don't want something big since space is a premium and i think a big change in size might be disruptive. I went after 19" but i only found 1366x768 rez. I suppose that is too low.

Any advice?

[forton]

If you are used to look at a certain resolution per inch of screenspace on your laptop try to match that somehow, if I look at my 24 inch HD monitor after working on my laptop it feels really lowres.