Since you are having Wifi connectivity issues from your PC and not other devices, using a USB Wifi Dongle may make a difference. However, you may want to change the Wifi channel on the router, first. Sometimes, interference from the router's coverage zone can cause connectivity issues. The Wifi channels you can use are 1, 6 and 11. If changing the Wifi channel solves the Wifi connection issue from your PC, a dongle will not be needed.