Experiment with disabling IPv6 in Win7. Although I don't think this is actually your problem, I suspect the upgrade may have messed with your network stack. Disabling IPv6 (via the properties of your network card) will force Win7 to rewrite the options stored in your registry and may solve the problem.
If that doesn't work, just uninstall everything to do with your network card, and reboot. Windows will reinstall it all. If you are using an onboard Nvidia card, you can download and install the latest nvidia chipset drivers which also may resolve the issue.