Thanks for useful advice on this thread but I have tried everything in this thread, to no avail.
I have downloaded the following drivers
for the wireless card (R256972 and R242432 from Dell) that are supposed to be the specs for my laptop and settings, but refuses to install as "appropriate hardware not detected"
Windows 7 Professional x64
Dell Inspiron 1545
Dell Wireless 1397 WLAN mini-card
Broadcom File Version 22.214.171.124
Any tips please?