Most wifi cards is or using ndiswrapper it works.
Problem comes in when loading the ndiswrapper module and unloading the other modules.
Have a look at http://www.sabayonlinux.org/forum/viewtopic.php?t=8933
If after this you still have bugs then shout and we can see what can be done.
Also check the wiki on top of this page + gentoo.org / forum / wiki .
You should remember to unload the other wifi modules (modprobe -r something) or (rmmod something) and then "modprobe ndiswrapper"
99% of it is in that link for ndiswrapper + all the links at the bottom of the post.
Hope this helps.