I just got the WNDA4100 yesterday and here are my first impressions. First, I am using the WNDR4500 Netgear router. I have been using it for about 3 months and have been very happy with the router. It has been very reliable since the last firmware update (v184.108.40.206). My router and PC are on opposite corners of the house, about 60ft and 8 walls. I know 5GHz does not do well penetrating walls but I wanted to see what it could do. My laptop with 802.11n and a single antenna at the same distance gets 72Mbps, the max it can get with 1 antenna. My desktop PC (Dell Inspiron 531/Windows 7) has a 802.11g PCI card adapter and gets 54Mbps. I wanted to upgrade since I have been working on some large video files that take 15mins or more to backup. I also wanted to try out 802.11a (5GHz). With 3 antennas in the adapter 2.4GHz max is 216Mbps and 5GHz max is 450Mbps. The WNDA4100 is a large USB adapter. It won't fit in my PC directly so I had to use the connector cable. Using the cable is a good idea since I could easily hit the adapter if it was plugged in upfront. I installed the software from CD and everything installed correctly. The router has an SSID for 2.4GHz and one for 5GHz. I disconnected from the 2.4GHz SSID and connected to the 5GHz SSID. I was not getting the expected performance. I was getting 54Mbps. I started inSSIDer to see what was going on. I rebooted and it did not fix it. I was finally able to connect at 162Mbps. I think inSSIDer was causing problems with the connection. I was only getting 3 bars (-80db) with 5GHz so that explained the 162Mbps and proved my concern about 5GHz penetrating walls. I then disconnected at 5GHz and connected at 2.4GHz. I got 4 bars (-60db) and connected at 216Mbps, the max. I then tried to ftp a 1G file to my NAS server. It took 3mins versus about 15mins. I am happy. I plan to try it on my laptop at a closer distance to see if 802.11a @ 450Mbps is possible.
Side rant. I am looking at getting a new laptop. A laptop usually lasts me 5 years so I want it to support 802.11a as well as 802.11n. I want it to have 3 antennas so I can get the max connection speed. I am willing to pay extra for an option to upgrade wireless networking. I just can't believe the new round of laptops coming out don't offer this. I found the Dell Ultrabook supports 802.11a with 2 antennas but other than this high-end model I have not found one.