They don't come from Microsoft, they come from Dell. If you don't have them on CD, download them from their site.
Look in Device Manager to see the status of all devices.
What, by the way, is "a new/used mobo"? Did you install that yourself? Then there might be a problem with the built-in Wifi hardware.
I have a Inspiron 5160 with Windows XP SP3 and am trying to get the wireless internet up and running. I do not see a wireless network connection icon in the network connections page. This is a new/used moboard, just did a fresh install of XP. Not sure if the adapter or driver is installed. How can I tell what I have? Can anybody help?