I can tell you that with my D-link DWA-140, the drivers from the CD were not good at all and the software that it installed was just as useless. The software also used cpu cycles for no reason and only wanted to use wireless G for some reason.
I have the exact same router as you do by the way, using the latest firmeware version 1.33NA, but my adaptor is a different model so no telling if this procedure will help in your case but it's worth a try.
How I fixed this problem was to unplug the adaptor
from the USB port, uninstall the Dlink software through add-remove programs and uninstalled the driver from the device manger.
I shut down the machine and plugged in the USB adaptor, rebooted and let Windows install it's own drivers for the DWA-140.
After that I used the built in Win 7 wireless connection set up and made sure to set it to use wireless N and AES only encryption only "not mixed"
. Your new Windows 7 drivers are linked at the bottom of this page.
I also went into my routers manual wireless set up and set it to use WPA-2 AES only
and set to use N and G only
, along with standard DHCP setting.
I scanned the area and went with channel 7 because nobody around seems to use that one. I used Xirrus wi-fi scanner for this. Xirrus: The Leader in High Performance Wi-Fi - Advanced IT Wi-Fi Networking Tools
This was for my garage computer approx. 60 feet from my router through two walls and with a few palm trees in the way. I also use the USB extension to get the adaptor pointed towards the house.
The signal strength stayed the same at two bars but the connection speed went from 2.98Mbps to 14.98Mbps, huge difference between N and G speeds and despite only having two bars the connection is perfect and very fast.
With this type of speed I can stream HD movies out to my gargage, not a single skip or stutter problem testing a bunch of movies, even with two bars.
The Anthros drivers are supposed to work better for your PCI adaptor. Dlink forum explains this in the link below.
Source> http://forums.dlink.com/index.php?topic=9799.0 For the new Windows 7 drivers scroll down to Kyjibo's post and click on the second link in his post where it says "here" Link for this below. Use the second set for Win 7. http://www.station-drivers.com/page/atheros.htm
Good luck, let me know if these new drivers work for you.