I upgraded my system to Vista x64, but I cannot find any drivers from the manufacturer (I read on other forums that they are not giving any further support for this card and they aren't giving 64bit driver support to any model), neither a version for XP x64, or compatible drivers.
I only find working (but not original thanks to DLink) drivers for the DWL-G520, but that's a different model, those drivers don't work for me, mine is '+'.

Support Information:
Device Type: Network Adapter
Manufacturer: D-Link Systems
Model: DWL-G520+
Interface: PCI / ISA
Operating System: Windows Vista x64
Age of Device: < 2 years old
FCCID:

Find it on DriverGuide (http://members.driverguide.com/index.php?action=srch&sm=b&aax=&qa6=327&qa5=12&qa7=1800&dp=2&qm0=DWL-G520%2B&jmd=and&fzz=d) | Find it with Google (http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=D-Link+Systems+Network+Adapter++DWL-G520%2B+Windows+Vista+x64+) | Research manufacturer D-Link Systems (http://members.driverguide.com/index.php?action=getinfo&companyid=327)

DLink doesn't state what os's their drivers are made for so you may just have to try some of them to see if they work in your newer os.

http://www.dlink.com.au/tech/Download/download.aspx?product=DWL-G520%2B&revision=REV_A&filetype=Drivers

In the support page it says their drivers are for 98/Me/2000/XP, and none of them worked for me(I already tried them), neither for all the people with 64 bits OS (on other forums there is a lot of people in the same situation like me)

Hello , I hvae the same problem, did you find the driver for XP64 o Vista 64? mi email is no.email.addys@allowed.com
Thanks for advance

Roberto Del Villar