What wireless card should I buy for Dell Optiplex 780 slim?

[jfarmer]

What wireless card is required for the Optiplex 780 slim? The unit has never been used, except to load software. However, it does not recognize the wireless card and I'm afraid the card is bad.

 

[RealBeast]

I would just get a USB wireless adapter, like this for example: http://www.newegg.com/Product/Product.aspx?Item=N82E16833704045