Actually Dell is working on a combination GPS/WIFI unit, if my memory serves me correctly, however that isn't likely why you got two different answers. If you had asked three people you would most likely gotten 3 different answers. Also, that combination isn't available yet to my knowledge.
The long and short is they (sales, customer service and even support) just don't know their products that well.
You didn't mention "which" model netbook you were talking about. It coulkd help to know.The models I'm familar with from Dell are conventional.
Generally it has been advised against having the built-in GPS for reception. It will have limitations compared to a USB with extention cord or Bluetooth receiver.
I have set up two Dell mini 9's. One with a bundled MicroSoft Streets & Trips 2009 gps/software and one with Garmin Moble PC 2009 gps/software bundle. Both with corded USB receivers. Both work just fine.
MS S&T requires 1024x800 min. resolution, The Dell mini 9 is 1024x600, however I was able to adjust resolution to 96% of that and it works. This is on my wifes netbook. There is a button that is a bit hard to get at but not impossible.
The Garmin install on the second unit is fine across the board.
A very good forum to check out is
http://www.mydellmini.com/forum/
Tell them bunjin sent you. ;-)
Hope this helps.