The range with the standard equipment is exaggerated by all suppliers. Divide their claims by 3 for more realism. Also outside inteference is a factor. rain, trees, wet trees much worse.
But anything is possible if you choose suitable equipment.
D-Link for example make high gain anntenna for their equipment to extend range. See here (bottom of linked page):
http://www.dlink.com/products/Digita...1bWireless.htm
Or Linksys do similar.
There is a forum here that has some range discussions:
http://www.dslreports.com/forum/rema...wlan~mode=flat