If the netbook came pre-installed with XP, then you would want to make sure that all your hardware drivers especially chipset drivers were updated and compatible with Windows 7. So you may want to follow up with the driver updates from either the packard bell site or the manufacturer's website for a particular hardware device.
Additionally the wireless network device seems to be pretty common in several netbooks from several different manufacturers, Acer, Gateway, as well as packard bell. What is the driver version that you currently have installed? The latest one I could find was 8.0.0.225 dated October last year (Win 7 RTM release date) I would have hoped a newer version would have been released by now, but I can't seem to find...