Drive Snapshot (Score 1)

Drive Snapshot http://www.drivesnapshot.de/en/ It's not freeware, but it works great and it has a differential snapshot function. You should be able to create a snapshot of your master install. Install the next software package. Make a differential snapshot. Shake and repeat. When you're done, you'll be able to mount the different snapshots using Drive Snapshot's Viewer and make comparisons between the installs, etc. Have fun!