I have a 13" macbook air (the new late 2010 model, upgraded CPU, memory) that has the following problem: I can connect to wifi networks (including at home WPA and also tried WPA2 settings) but even though I may get proper speed at first, I soon lose that (permanently even while disconnecting and reconnecting) and it becomes much slower and choppy (if I open activity monitor I can see the speed going up and down like crazy...). My internet speed at home is 12mpbs set by my provider. When I perform speed tests (vis speedtest.net or downloading files from other speed test sites) on my windows PC that is also on this network I get the full download speed. However with this MAC while I initially did get the full speed, it is now down to an average of 3-5mbps and the activity monitor, again, shows choppy behavior so it will be at 8 then at zero almost and then up and down again but never near the full speed. I tried to connect to other networks and I have the same problem - once this happens it stays. I tried removing the airport connection in network preferences and adding it again it does not help. I TALKED TO APPLE AND HAD MY COMPUTER TESTED BY THEM - they didn't find any hardware issues (they said it was fine - but it isn't) but they still replaced the airport hardware in the computer - both the chip and the antenna (which meant replacing the entire screen). I brought the computer home, ran a speed test and everything was fine. I thought GREAT but then something happened and the problem returned. What I did (which I think was unrelated) was connect via SMB to a PC at home and I tried to stream a movie file. I noticed it kept 'pausing' so I opened up activity monitor again and to my HORROR I saw the choppy wave with network speed very inconsistent going up and down like crazy... I tried connecting to my slingox using the sling web access after disconnecting from my home PC but got partial speed and lots of drops too. I tried the speed test again multiple times, nothing seems to work. SO I don't know what to do at this point. I have 10.6.6 running. I heard something about a firmware update but I am new to mac so not sure how to even do that or what else I can do to solve this problem or what is causing it. BTW - logging in now from the guest account still does not fix the issues and they remain the same. I am desperately looking for help!! Thanks a lot!