After reading the messages about superior performance from the Intel 5300 wireless network adapter, I bought one from ebay.
One of the screws holding the original adapter in place was so tight that I had to drill it out. That was scary!
The new adapter is one of the itty bitty ones. I installed it, using some double-sided foam tape to hold it in place, then installed the drivers recommended here. Everything worked fine, although the new card recognized fewer available wireless networks than the original card. (I like in a townhouse complex so there are lots of wireless networks in my neighborhood.)
When I went to visit a friend, whose wireless network I set up and use frequently, the new card did not recognize any available wireless networks, although another computer was able to connect without a problem.
I put the original card back in and it found the network without a problem. Later, I reinstalled the Intel 5300, deleted the drivers and reinstalled them, and it recognized the network at my friend's house. However, when I got back home, it didn't recognize my network even though it's sitting less than 2' away from the router.
I reinstalled the original card and it found the network.
I've contacted the seller, but am posting here just in case one of you gurus recognizes something that I'm missing. I got the 5300 card because there's one location I use that has a low signal (I'm fairly far away from the router) and hoped that the Intel card would receive a stronger signal.