I was unable to install SQL Server 2005 Management Studio Express on a Windows 2008 Server… I tried to re-download the package and many other tips… at the end I found this: http://community.visual-basic.it/alessandro/archive/2008/04/21/22626.aspx

so:

1) start CLI (“dos”) as “run as Administrator”

2) then launch the install process with this sintax MsiExec.exe /i C:/SQLServer2005_SSMSEE.msi

3) follow the install process… and WOW, no more error!