These speakers are passive - there is no built-in amplifier. So you would need to add an amplifier with a USB input - the recently launched NAD D3020 has had some excellent reviews.
But if this stretches your budget more than you had intended, here are some active alternatives with their current RRP's. These can just connect straight to your laptop without the need for extra boxes.
£250 Monitor Audio Airstream WS100
£300 Ruark Audio MR1
£300 Focal XS Book
£600 KEF X300A