"HTTP 500 Internal Server Error" after installing Sharepoint 2010 on Win 7

After completing the configuration wizard, you get a HTTP 500 error instead of the Sharepoint site welcome page.

Check the required features in the IIS section of the Windows Features dialog box (which you can access through the Programs section in Control Panel)and make sure that ASP .Net is checked.

I hope this helps.

Source:
http://msdn.microsoft.com/en-us/library/ee554869(office.14).aspx