I downloaded the latest iTunes version and got the same error message.
After a lot of trial and error and research on the Internet I found a
solution that worked for me. I hope it also helps other users trying to
install iTunes on Vista.
1. Start Menu -> All Programs -> Accessories -> Right Click on Command
Prompt -> Run As Administrator.
2. If you don’t end up in the C:\windows\system32 folder, go there
3. Once there type in regsvr32 vbscript.dll and press enter