Wrong variant of wireless card or wireless card is disabled with [Fn] and [F2] or just [F2]. To check the wireless card provide the hardware IDs see here: [URL]
I really need some help on this, I've spent hours trying to figure this out.  So I just recently formatted the hard drive on my Inspiron M5010 and reinstalled Windows 7 Home Premium 64 bit.  After installing Windows, I began to install the drivers in the order recommended by the Dell Support website.  I installed them in the following order:
Error installing Dell Wireless Driver on Inspiron M5010