Windows Installer 4.5 is now available as a redistributable system component for the following operating systems:
Windows Server 2008, 32-bit editions
Windows Server 2008, 64-bit editions
Windows Server 2008, Itanium-based editions
Windows Vista
Windows Vista Service Pack 1 (SP1)
Windows XP Service Pack 2 (SP2)
Windows XP Service Pack 3 (SP3)
Windows Server 2003 SP1
Windows Server SP2
Refer this link for more details !!!