Try moving the router to a central location in the house. Also, right-click the wifi connection in the lower right of your screen and set the priority of your router as the first to connect. If you go to multiple locations or have a neighbor with a wifi router, your laptop might be trying to connecto to it, occasionally.
I have a trendnet wireless router and my desktop is connected to the router with a cable.
I had an old laptop with a trendnet pc card and my speeds and connections were great.
The problem is with my new laptop. I no longer have the old laptop. My new laptop has a broadcom internal wireless adapter and the speeds were really slow.
I took off the security and set a MAC filter list.
My speed is good now, but I keep losing my connection for no reason!
When I reconnect it works fine for a while, then it's gone again. I have changed from channel 7 to 6.