Recommendations for USB WiFi stick

[#1]

My Thomson router is only 5m from my PC but I struggle to open any Internet sites (but email is ok). However, my laptop in the same room works fine. Both use XP SP3. I assume then that my Edimax USB WiFi stick is the problem. Can anyone suggest an alternative make/model or if there is anything else I can do to fix this issue?

[#2]

I just bought the buffalo mini wifi usb WLI-UC-GN
Really good. Though make sure it IS the USB stick before you spend anymore money. Turn the wireless off on your laptop and try and stick in there.

[#3]

As jamesg1979 says try the USB adapter in the other system first. Also might be worth checking that you've got the latest driver for the adapter (at http://www.edimax.com/en/support.php?pl1_id=1&mwsp=1).
Depending on where you live and how close you are to other properties it might also be worth checking for other active WLANs using the same channel as you. I've found inssider (http://www.metageek.net/products/inssider) handy for this.

[#4]

Thanks for your suggestions. Have tested stick in laptop with internal WiFi disconnected and it works fine. Have upgraded to latest driver and changed channels but  still having problems on the PC. Driver is identical on both machines. IE8 on both as well. Any ideas what next?