I'm pretty sure laptop use is excluded from web and walk.
EDIT: yes, specifcally excluded "Remember that you can only use web'n'walk in the UK and you
can't use your phone as a modem or use web'n'walk for peer to peer file sharing, instant messaging (except if you have a Sidekick) or making internet phone calls."(my bold)
Go here and click at the bottom of the page on terms and conditions
http://www.t-mobile.co.uk/services/m...ing-customers/