Whoops, didn't see your screenshot there. I'll check with the installer team and see if they can help decode this error.
A couple additional questions:
- Are you running as an Administrator? (Have you tried right-clicking and choosing 'Run as Administrator'?)
- Do you have any special security configurations on your machine (antivirus, corporate security, etc)
- Which version of Vista are you running? Is it SP1?
My best guess without further data is that your install is failing because you don't have admin rights. Try running the installer as Administrator, and let me know if you still have trouble.