I am sorry you were having troubles, although its obvisouly too late perhaps others can benefit form this thread.
I have successfully setup the MN520 on Redhat and Fedora using this process, although I am sure it would work with just about any distro:
1. type: su (to root)
2. type: /etc/pcmcia/config /etc/pcmcia/config.bak
3. type: vi /etc/pcmcia/config
3. type 'i' (insert mode), then Put or type the following entries into /etc/pcmcia/config file right after the line that reads "# Wireless network adapters":
card "Microsoft Wireless Notebook Adapter MN-520 1.0.3"
version "Microsoft", "Wireless Notebook Adapter MN-520", "", "1.0.3"
bind "orinoco_cs"
4. Hit 'Esc' and type: ZZ to exit vi (saving changes)
5. Restart the system.
The card will be detected "Lucent Orinoco and Prism II-based PCMCIA wireless". and the "Wireless" LED on the adapter will start blinking.
This process and config for other distros are discussed here:
http://www.cuddapahonline.com/techno...inux/wireless/
File it under 'For what its worth'.