The easiest way to deal with the Vista complications is to not put the game into C:\Program Files. Personally, I keep a C:\Games directory that all my games go into (other applications still go into C:\Program Files).
If you're happy to do it that way, you can just copy it straight off the USB key. The very first time you run it, you'll get an error that it couldn't initialise the fonts and the game will exit. Run it again and it'll work fine.
If you want it back in C:\Program Files then you need to deal with the fact that Windows won't let you store the game data under C:\Program Files, and will move the data files into your own directory. Here's how I'd approach that way:
* Install TCB normally. You can get the installer from
http://forum.caravelgames.com/downloads.php if you didn't keep a copy.
* Run TCB once and then quit it straight away.
* In Windows Explorer, browse to C:\Program Files\DROD - The City Beneath.
* In the menu bar of Windows Explorer, you should see a Compatibility Files button. Click that, and you should end up in a directory that starts with C:\Users.
* Paste your old TCB Data directory over the one you see there. Don't paste the files that sat above the Data directory in the main TCB directory.
That should do it.