I didn't "read" the question, it's not an issue of installing a program but a question of keping track of the registry when you alter your setting.
My first reply to this question is a great way of keeping track of a new install.

Shawn
Nice and functional!

If you don't have a clou in whitch key to look in and diskspace is not an issue, but Your time is, why not export the total registry:

1) Close ALL open windows (quiet your machine)

2) Go Start->Run "regedit"

3) Hi-lite My Computer

4) Select Registry->Export Registry File... from the menu

5) Go File_name: c:\Before (the extention will default to .reg)

6) Make your change ( ie set your pagefile size or whatever )

7) Set focus to regedit again and hit F5

8) Hi-lite My Computer

9) Select Registry->Export Registry File... from the menu

10) Go File_name: c:\After

11) Pull-up a dos command window

12) Enter: FC Before.reg After.reg >Diff.reg

13) notepad Diff.reg and look for relevant changes

14 ) Delete C:\Before.reg and C:\After.reg