Yesterday, I have installed Vista and my Internet stopped working. You could find that post here.
The problem is not with Vista but with theÂ Security Software I am using, Live OneCare from MS.
Apparently there is a problem with OneCare firewall that prevents Internet connection
The solution I found out was
“The only solution I have found so far is to turn off the OneCare firewall (until they release a fix) and to turn on the regular Windows Firewall.Â It warns you against this and my OneCare is now red, but I can connect to the Internet through my wireless router.”
from a forum post.