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You need to give us some more details to get help. What exactly is the model of Dell, laptop? Can you look up the spec and find out what WiFi network card is installed in it and let us know? If you can find them, details of the WiFi chip would help as well. (
No Internet connection... Yeh, I know... Read on...)
You're probably going to need to install a software module to enable the WiFi so the other thing you'll need is a Cat5 network patch cable to connect between your netgear router and the laptop to give you a connection to the Internet to allow you to check specs and download the correct module. Wired connections just seem to work!
Every time I've upgraded the OS on my old EeePC netbook it loses it's WiFi and I have to re-load the Realtech module this way to get it back.