The MSI file format is used to hold information about configuration and installation by Microsoft’s Windows Installer . Some benefits are the rollback feature, repair feature and on-demand installation of program features. But if there is a problem with Windows Installer on your computer, you will generally face problems and errors [e.g. "The feature you are trying to use is on a network resource that is unavailable"] while installing MSI packages.
For such a situation, there is a freeware software called Universal Extractor which can extract/unpack MSI files to a temp folder. Not only that, it can also unpack many other types of compressed files like Zip, RAR, ACE, 7-Zip, Bin, Cue, Cab and even EXE files. (and many more)

Download Link- http://www.c1pher.com/uniextract131.exe

Update: Universal Extractor has been upgraded to version 1.5 which can be downloaded here. Known to work partially with Windows Vista.