Newbie connection problems

I have a tplink ap/router and tplink wireless cardbus adapter. My desktop is connected to one of the ethernet ports.Laptop with wireless adapter.When I try to connect to ap its dhcp server wont assign an address for laptop,but it does for desktop(ethernet).If laptop is connected to ethernet port there is no problems at all.When I assign ip to laptop(wireless) in the right range as router and desktop it connects but I cant see or access lan.I ping the ap/router and it only returns about 10% of the time.
Same if I ping desktop.Both machines have win xp sp2,no firewalls and no encryption.Im about 5meters away from ap with nothing in the way.Signal strength according to computer is good to excellent.Ive used card software as well as windows but its still the same.Ive also tried different channels and speeds.Any suggestions

Thanks.

Have you tried upgrading the firmware in the AP/router and the drivers on the laptop?

It's not a good sign that you're getting 90% packet loss when pinging the router from the laptop. It could be a faulty AP/card, but try update to the latest firmware/drivers first.

Hi there. Did you try this setup with encryption on first? If so you may find that is still trying to apply the security key. You need to delete any profiles that might be saved on your laptop. If you can find them the easiest way is to just change the SSID on your AP, and then reconnect. Since the AP and card are made by the same manufacturer I doubt that there is an incompatibility. If you can't work it out you are best to factory reset your AP and start again as you most AP's let you connect straight out of the box.
Good luck
Dale

Thanks for advice. Ive upgraded ap with latest firmware.Cant download latest drivers for card the file is always corrupt Ill keep trying though. Followed link from wireless section and downloaded atheros drivers but keep having same problem.Reset ap no difference.Deleted all profiles best I could and changed ssid still no difference.I suppose without another ap or card I cant tell which is the problem device? They are both new so I suppose a long trip back to the shop.

Thanks again.