|Well - it kinda looks like you have gone through most of the things I would check, but here are my ideas anyway|
1. Can you ping the loopback address?
If you can ping the loopback address then it generally means that vista is configured correctly
2. Could you access the internet using the UBCD4WIN/ Any live linux distro? If so then it could be a driver issue
3. Does disabling the installed firewall help at all? Even windows firewall can mess up sometimes. Try disabling it and see what happens
I dont know if you have already tried these, but I thought I would add them in and see if they helped at all!