I am posting about your idea on what's wrong with my Lifebook S6010. It comes with a built-in Intersil PRISM wireless NIC card which I use constantly.
Just recently, I get very very slow speeds when trying to access a website or anything. It appears as "Very Low" and at a speed of 1.0 Mbps according to Windows Wireless Network Manager. It takes forever to surf the net and is very inconsistent. Sometimes pages will load quicker (despite the amount of content) and other times it takes a minute to load the text (excluding images).
On a somewhat consistent basis (roughly every 15-20 minutes) it will disconnect and re-connect again taking about a minute to do so.
I know it's not the network since multiple computers are connected and roughly the same distance away. Currently I have my desktop with a wireless card picking up a strong signal but my Lifebook picks up a very weak signal even though they're both not that far apart from the network.
Could the NIC card be weak or running on its last leg? Or is there some reputation with PRISM NIC cards?
Any ideas or suggestions are appreciated!