Connect my Windows XP to Mac OS X Internet Sharing
WOOHOO! think I finally solved the problem.

From the taskbar I right-clicked on the MacOSX network and hit configure...(which now shows up as properties...) and saw that the security type had defaulted to none even though encryption type was still set to WEP.  I changed the security type to Shared and it now works.  It took a few minutes to register the network and only once I changed it to a home network did the internet connectivity kick in.  A 40bit wep key works fine, ABC12 or 4142433131...