see if the information in this thread helps. I know it is refering to vista but itis possible win7 has the same drop out problems in wireless that vista has and usb wireless is not always the best of connections. http://www.hardforum.com/showthread.php?t=1380507
How are you having ethernet issues? All you have to do is connect a Cat5 straight-through ethernet cable from the routers RJ45 jack to your computers NIC RJ45 jack. You can go to pretty much any store these days and purchase a PCI 10/100 NIC for 20 bucks.
When you get into wireless, there are all KINDS of problems. Attenuation and Intrusion are just two.