What kind of laptop is best for cold wallet of Armory (with keypad or not)?

[RationalSpeculator]

I'm considering buying an old laptop so I can install Armory on it and have a cold wallet. (the laptop would never be connected to the internet again)

Also I will sign my transactions on that laptop. Somebody said he regrets having bought a notebook for it as it is too small to sign transactions comfortably.

I'm doubting between buying a laptop, without keypad on right of keyboard, or with keypad. I like the keypad to insert numbers but it makes the laptop big. So I was wondering if you can sign transactions without using numbers but only letters?