The offer has been suspended at the moment as they have run out of PCs, although looking at their prices they dont seem that bad. However its the 3 year contract is how they make their money, try and leave before then you would have to buy your way out of the contract.
Perhaps a "better" offer is the PCWorld and Orange one
here, a free laptop (Or discount on any laptop you choose) when signing up for 24 month Orange Broadband at 15 quid month.
Jen