Quick Tip: Sharing Ethernet Connection from OS X to Vista Using Airport
I seriously reached the end of Google trying to figure out why Hayley’s Microsoft Vista laptop would not connect to my Mac for wireless internet connection sharing. I was messing around with the wireless network connection settings on the Vista computer (Control Panel -> Manage Wireless Networks), and it finally connected after I enabled Shared security in the Security tab of my wireless network. I also have WEP enabled, which is the only thing available on my OS X 10.5.8 MacBook.
Just thought it might help somebody.