root@TheBox:/usr/src/ipw3945-0.0.70# make

 ERROR: ieee80211.h not found in '/lib/modules/2.6.15-18-686/include'.

You need to install the ieee80211 subsystem from http://ieee80211.sf.net
and point this build to the location where you installed those sources, eg.:

% make IEEE80211_INC=/usr/src/ieee80211/

will look for ieee80211.h in /usr/src/ieee80211/net/

make: *** [check_inc] Error 1
root@TheBox:/usr/src/ipw3945-0.0.70#