sharepoint 2007 installation error about asp net v2.0

if you receive this error, After clicking the setup file to  install Sharepoint 2007

Setup is unable to proceed due to the following error(s):
This product requires ASP.NET v2.0 to be set to 'Allow' in the list of Internet Information Services (IIS) Web Server Extensions. If it is not available in the list, reinstall ASP.Net v2.0.
Correct the issue(s) listed above and re-run setup.


then run , aspnet_regiis -i under c:\windows\Microsoft .net\Framework\v2