http://support.dell.com/support/topics/global.aspx/support/downloads/en/driver_install_order?c=us&l=en&s=gen&~lt=print

Having the same problem right now... anybody knows how to solve it?

Thanks in advance.

Finally I telephoned the technic assistance of dell, and they gave me a solution :

http://support.euro.dell.com/support/downloads/download.aspx?c=es&l=es&s=gen&releaseid=R287498&formatcnt=0&libid=0&typeid=-1&dateid=-1&formatid=-1&source=-1&fileid=427728

Looks like the drivers in the CD are not the correct for the WIFI. This one, the R287498.exe, worked fine for me.

Good luck!