Program to snapshot changes made during an install?
Solution 1:
There are several ways of accomplishing this. One of my favorites is using WinInstall LE (a free product which has changed hands many times over its lifetime) to capture the installation package. The same pre / post snapshot method is available in many products. It'll detail exactly what changes are being made.
You can also use a couple of the sysinternals tools to do the same thing but it tends to have more background noise.
Solution 2:
I haven't used it personally, but I have a few developers who vouch for it; ZSoft Uninstaller. It's free.
Here's a walk-through for it too!