You’d be hard-pressed to find a laptop these days that didn’t have wifi built-in but if your service is sketchy, or the built-in just can’t lock on to the free McDonalds wifi down the road, then try one of these USB Wifi Mini Wireless Adapter doovers. The tiny little USB dongle support an enormous 5dBi antenna. The specs claim an operational range of 200m indoors and 830m outdoors, conditions permitting. I’d say quarter those numbers and you might be close.
The best bit is that it has an RP-SMA aerial connector, so if you don’t want a whopping great aerial upsetting your typing, get a cable extension and you can put the aerial anywhere. US$23 from Brando.
# Standards: IEEE 802.11g(draft), IEEE 802.11b
# Effective Working Distance: 200 meters farthest indoor and 830 meters farthest outdoor (varies due to the environment)
# Frequency Range: 2.4~2.4835GHz
# Number of Channels: 13
# Support the Network Protocol: CSMA / CA with ACK