It sounds like a driver issue.
I assume you mean the card worked previously on an old motherboard.
Remove the wireless NIC driver and then re-install it. I assume their are no yellow exclamation marks agianst your NIC in windows system properties? To see sys properties right-click "My Computer" select Properties/Hardware/Device Manager. Look for the network adaptors section. You can update drivers from here on your wirless card or even try the Troubleshooter tab.
if you don't have the driver CD let windows go onto the internet and search for a driver.
If you rely on the wireless card to connect to your internet connection, perhaps you can connect your computer to the internet modem or router via your computers LAN/network connection?
If that's not possible, download the driver from the NIC cards manufacturer website and pop it onto a USB thumb drive which can then be installed onto your new computer.
Last thought, make sure you are only using one controlling application for your NIC ie you use either the Windows Zero Config Utility OR the NIC cards manufacturer utily eg D-Link, Netcomm, etc etc
That is not both at once as windows has a major hissy fit.

See:
http://forums.whirlpool.net.au/forum-replies-archive.cfm/438290.html

http://www.netcomm.com.au/__data/assets/pdf_file/0020/17291/61_Using.pdf

http://forums.whirlpool.net.au/forum-replies-archive.cfm/1378157.html


Cheers,
Steve