Wireless USB OR PCI?

My friend has a modem, so we went out and got a Dlink router, and set it up. He has a usb wireless adapter. From were the router is, to were his pc is, he is only getting like 2-3 bars of connection. When he plays bf2, he gets many connection problems, somtimes loses connection to the adapter. I know its the adapter thats not getting enough connection to it. He's not in a postion to hook up to the modem or router directly though. So he needs to go wireless. Does he need to go get a PCI Adapter to get a stronger connection. I can play bf2 fine downstairs on my pci adapter. But i duno if it would help him or not. Thanks for your help.

unfortunatly wifi ain't good for gaming.. but since this is unavoidable lets try some stuff...

-Try bringing that PC with its wifi adaptor as close to the router as possible and see if it improve its strength.
-Try different router position and see if it will give better coverage
-Move objects that may interfere the signal like CDs, metalic objects, radios/chordless items (eg phones, tvs, radios etc)
-try a bigger antenna, if the router's one is detatchable

Remember, radio signals travel in straight lines, and walls and other objects will degrade that signal bit by bit..

http://i9.photobucket.com/albums/a60/italianpimp316/pclayout.jpg

if you could get that router on the other side of that wall i think it would improve your signal alot.. otherwise use a usb extention cable to move the usb wifi closer to it...