Vista is notorious for connectivity problems due to a failure to identify the network you have connected to, it's that dialog window that comes up and asks you to choose "Home", "Work", or "Public" as the connection identification.
I have encountered this problem a few times when installing our internet service, on a couple of cases it has taken a couple of hours to get Vista to present that identification dialog, and unfortunately the chances were high that next time the person reboots it will fail to identify again.
1) Seriously consider switching to Windows 7, your life will be much better.
2) Continue to do the following until you get the dialog to identify the network or you smash your PC:
--- physically unplug and plug back in the network cable at the back of your PC
--- disable/enable the Local Area Connection
If you can get it to identify and connect to internet then the first thing you should do is get all available updates/fixes for your operating system, especially service packs if you are not up to date on those for Vista.
3) here is a link to a forum that has some different possible causes/solutions to this problem:
http://www.chicagotech.net/netforums/viewtopic.php?p=1377(you will have to scroll down in the thread a bit to find people talking about solutions that worked for them)
Good luck!
I will tell you my Vista experience, I put off using Vista for as long as possible, then I figured I needed to get familiar with it because of the work I do so I built a new computer and put Vista on it, I used it for about 4 days before I put XP on the new PC and NEVER booted to Vista again.
When Windows 7 came out I bought another hard drive and installed it, I have been using Windows 7 ever since.
Regarding enabling/disabling IPv6, well that's classic Vista for ya, I have seen it make no difference, which it shouldn't since IPv6 is not yet in use over the internet, I have seen disabling IPv6 STOP a PC from getting on the internet, makes no sense since only IPv4 is used, and I have seen once where disabling IPv6 did fix a connection problem.
