1. RF channel is same as neighbors. (change it!)
2. You are using something insecure like WEP (change to WPA/WPA2)
3. You are sharing the air space. Drop is expected but some don't get why or want to know.
I have a wireless network, Dell laptop and Dell desktop, Netgear WGR614 router. Desktop works fine. Both systems are running XP and IE8. Laptop was working great until about a week ago when it slowed down to nothing when loading webpages. Outlook Express works fine. Speed is normally 54 Mbps but drops suddenly to 24 Mbps. I downloaded Firefox (took forever) and it has the same problem. I checked the settings in IE8 on the laptop against those on the desktop and they are the same. The laptop is in the same room as the desktop. I did recently buy an iphone 4 on Verizon and it uses the wireless network. Any ideas on what to try?