Ultrabook purchase help

I'm researching on behalf of a good friend that is at university and is in much need of a lightweight ultrabook. His budget is £400-450 ($450 dollars) and it must be 1.5Kg in weight. Its a specification that leaves very little for maneuver I admit. I am not that familiar with the mobile market and was hoping that there would be some guys on here that would be able to help us out.

Thanks. 

For some basic recommendations, it would be great if you could give us more details on your friends´ computing needs...
What subjectdoes he study?
Does he have to use any specific software for his studies?
What are his requirements regarding memory, battery life, speed?
Also, what would he use the ultrabook for, most of the time? 

regards, Julian