There is not an official Windows 7 driver available for the AccelePort Xp cards, but the latest driver for Windows XP/Vista/etc does work. The OS will fail to detect a driver at first, but will display the card in Device Manager as not installed properly. You can then point the OS to the driver that was downloaded from the Digi site and it should work from there. The latest driver can be found here:
http://ftp1.digi.com/support/driver/40002544_c1.zip