I would check out this support documentation from Windows. From the sounds of it, the Windows servers are too busy, or an AV, or firewall program is preventing you from connecting. What AV or firewalls do you have installed, if any?http://windows.microsoft.com/en-us/windows...-error-80072efd
If you have already tried these solutions, we could use some more info. What service pack is already installed? What type of computer, etc..
When did you start having this problem? Can you connect to the Windows website? Can you connect to other websites? There is a problem upgrading to service pack 2 from Vista SP1 that I am aware of, but we need more info.
The more information you can provide the better.