If the Transformation Pack replaces system files (and I'm almost sure it does), it'll affect the entire system, including your main user account.
Rather than creating a new account, which wouldn't do much good, I'd suggest imaging your drive (which is a good practice anyway) or creating a System Restore point at the very least. With that said, if the Tranformation Pack uninstaller is done properly, it should revert your system back to its original state.
In order to change shell icons, progress dialog animations etc, the Transformation Pack would need to patch/replace systems files, including shell32.dll and explorer.exe among others. These are not per-user files, so any changes to them affect the system as a whole.
And yes, it can be uninstalled, but if, for some reason, the uninstaller fails to revert the system back to its original state properly, every account on the system will be affected for the reason mentioned above. It's always best to have a backup of the system before you attempt to install anything that patches or replaces system files.
Ep, glad to see you come back and tidy up...did want to ask a one day favor, I want to enhance my resume , was hoping you could make me administrator for a day, if so, take me right off since I won't be here to do anything, and don't know the slightest about the board, but it would be nice putting "served administrator osnn", if can do, THANKS