well cus i think an mst just sets options like parameters where as i had to actually remove a component from the msi. i don't actually know a great deal abot it and i was only stabbing in the dark when i tried editing the msi in the first place. <{POST_SNAPBACK}> Actually, anything you edit on the msi can be done with an mst file. You can edit the mst to add registry entries, modify the public properties, remove a custom action, remove a component, etc. One more advantage of that is the file size is smaller compared to the msi, so it's easier to distribute. I have nothing against editing msi's. I also do it myself. However, it's not the best practice. That's why they make mst's.