Help Me Set Up My Son's PC for Wireless

My wireless router is on one end of the house, my son's pc is on the other. I bought a Linksys Wireless-G USB adapter for his pc, but it barely gets a signal.
I know the adapter works because it's hooked up to my other 'puter right now.
My wife's laptop works fine wirelessly in my son's room. No problems at all. I figure that the USB adapter just isn't picking up the signal as well as her laptop does.

The way I figure it, I have two options:
A) Move the router to a more central location of the house. Or,
B) Buy a more powerful wireless adapter.

I'd rather do option B.

Suggestions?

Thanks in advance.

 

here's an internal card with a larger antenna
http://www.newegg.com/Product/ProductReview.aspx?Item=N82E16833315041

my guess is you can look for something similar to this.