The installation doesnt overwrite any files without prompting first. I am not 100% sure you can install without admin rights since you need to copy files in the winnt/system32 directory. Since version 3.1.1 is in visual basic and uses the VB installer, it copies the VB run time files which get installed with any other VB application. Therefore, it might prompt you to overwrite those if they exist and are older. u can usually leave the existing files on the hard drive as they are and attac 3.1.1 should work fine.
It prompts me to update some system files or cancel the install...I click ok and get an error: Cannot update system file 'C:\WINNT\system32\regina.dll'. You may not have permission to update system files.