Gregory, this sounds like an extremely well thought out plan. One we could all benefit from. Thanks for laying this out in detail.
Cecil

(1) installing sqlserver 2008 on Win7
The Install warns about a compatibility issue. You can ignore that. But after the install you have to install sqlserver 2008 sp1

(2) Install/uninstall
Since vista, you can do an image backup
Before I install anything significant - I take an image backup of my C: onto a USB drive
You then have to go into each folder of WindowsImageBackup in that USB drive - It then asks you to change the access permissions of the folders

After that I rename the folder - so that I have many image backups, eg

WindowsImageBackup_20091208_1_afteractivationBeforePrinter
WindowsImageBackup_20091210_2_afterprinter_beId_beforeSqlServer
WindowsImageBackup_20091212_afterSqlServer_beforeVS2010
If any installation fails or I want to go back to a point in time
(1) I put a text file with the name of the folder of the image I want to restore in the USB drive
(2) I rename the folder to WindowsImageBackup
(3) I do an image restore (you have to boot from CD)

All my data is on a separate partition D: which I back up every day with robocopy
I have put all the data of sqlserver on a separate partition E:

This means that I can restore the OS without touching my data

I rarely do an uninstall - I simply do an image restore