I bought a DWA-552 card with my new computer, and have been having my fair share of problems.
I am running:
Vista Home Premium x64
Core 2 Quad 2.33GHz
8GB DDR2-800
First off, my unit seems to be manufactured wrong, ie the connector doesn't reach fully inside the pci slot when the card is inserted flush against the mount on the case. I've confirmed that other cards mount without issue.
My first attempt at installing it with the included software seemed successful until I tried to connect to my network. Immediately out of the installer, the network was detected but later disappeared after I entered the credentials, etc. I've since tried installing the 1.50 drivers to no avail.
After the above failed, I uninstalled the D-Link software, removed the card, and installed it in my other slot to find that now the computer won't detect the card at all (I'm thinking due to lousy/nonexistent PCI connection). None of the D-Link setup utilities will complete because they can't detect the card either.

At this point I'm thinking of returning the card in hopes that perhaps my unit is defective and that another may actually work. But before I make an hour-drive to return it, did I miss anything? Any help at this point would really help, because frankly I'm out of ideas.