The script will check for the existence of the Unlocker-folder in %programfiles%. If it's there the program is already installed and the script will exit. You may skip this line if it doesn't apply to you, or just REM it. I've a had a few problems with Unlocker installing over and over again in some cases. The conditioned testing first, will solve that issue.
When install is done, robocopy will copy the unlocker185.txt-file to the install-folder on the client. It's just a regular ascii-txt file with the text "Unlocker v1.85 installed" in my case. 8-)
Get Robocopy from the Microsoft Download Center. It's free and very useful.
Tested and deemed ok on WinXP SP2 US-Eng and WinXP x64 SP2 US-Eng. Dito Win2k3 Std and Ent SP1/2 and R2 Ent SP1/2.