First decide how big you want your laptop to be. I mean what the weight to be and what the inches of the display to be. You can choose from:
8.9" and 10" which are with estimated weight 1-1.2 kilos.
11" -12" laptops with estimated weights of 1 to 2 kilos.
13" laptops with estimated weight of 1.3 kilos
14" laptops with estimated weight from 2 to 2.2 kilos
15" laptops with estimated weight from 2.6 to 3 kilos
16.4" -17" laptops with estimated weight from 3.2 to 3.5 kilos
Productivity- or what work you want to do with the laptop. From this depends what exact characteristics you will need your laptop to have
Entertainment- the powerful processor, the big memory and the good video cards turned laptops into movable entertainment tool. You can use your laptop to entertain in any way- listening to music, watching movies, playing games and etc.
It will depend on battery how long you can use your laptop in surrounding without electricity. So choose laptop with good characteristics of the battery (to be durable at least 3 to 5 hours
Wireless is what all the new laptops have. It is advantage that turns your laptop from movable entertainment center to movable working place. If you have wireless you will taste the freedom.
So in conclusion we can make the parameters of the perfect laptop in the following way: laptop with screen wide 12 inches, which is enough for work and enough for entertaining, at the same time this size is easy to bring with you and doesn’t not take too much place; with weight of maximum 1,5 kilos, because you do not need to feel as you are bringing burden all the time; with powerful processor; with long life of battery, if 6 hours is available it will be great, if not- 3 hours is OK; with at least 150 GB hard disk, as you do not need to think about running disk space instead of having fun; without DVD or CD as they will take place and your laptop will be not that thin, so just get additional one and bring it with you when you think there will be need of one; LCD display or if you have enough money sensor display which is more expensive; of course powerful video card, because you will watch movies, make presentations and so on; and obligatory 1 VGA port, 1 S-Video port, 5 in 1 card reader, USB port, camera and port for microphone and headgear.
And the final price I am sure will be just in your budget. Just search for good offers and do not deprive yourself from laptop.