I had an old Athlon XP with an Encore ENLWI-G PCI wireless card (uses chipset Realtek RTL8185) running Windows 7 x86, and everything worked perfectly.
I very recently did a "slight" upgrade to a Core i5 and Windows 7 x64, and I was going to use the same wireless card, but even though Windows finds and installs the driver (Marvell one though), it says "this device cannot start (code 10)".
There are dozens of reports of this on the internet, but none of them with a working solution.
After trying 3 different drivers, from Encore, Marvell and Realtek, and none of them working, including some obscure unsigned ones, I finally gave up and decided to seek help from the community.
Unfortunately going wired is not an option, because the computer and modem are in different rooms. Right now I have a 5 meter cable going across the house, but that definitely doesn't look nice, not to say dangerous, just waiting for someone to trip.
Anyway, worst case scenario, I really give up and buy another card.