If I understand your question correctly, you will have to create a wrapper to launch all MSI packages. Please note that MSI allows only 1 instance of Execute sequnce at a time. Hence, your MSIs will have to be run sequentially, not concurrently.
There are many tools out there that you can use to deploy software. SMS scripts, Active Directory, Login Scripts, Zenworks, Altiris, Tivoli, Spirian, and so on.