Shoutbox

Check Windows Update and download any updates. Restart your PC.

If you can't install the KB971644 Platform Update for Windows Vista, it contains the following updated technologies which you can download and install manually:

Windows Graphics, Imaging, and XPS Library (x64)
Windows Automation API (x64)
Windows Portable Devices Platform (x64)
Windows Ribbon and Animation Manager Library (x64)

Source: Microsoft Answers | Platform Update for Windows Vista KB971644

Try this offline installer link for WLM 2011 beta:
http://g.live.com/1rebeta4_all/en/wlsetup-all.exe

If still no luck, follow these instructions to update Windows Live Installer:
http://windowslivehelp.com/thread.aspx?threadid=f...-a40d-048245542d63

Source: Windows Live Solution Center | Windows platform update - Don't see it!