In my install I keep a clean version of the game in the official folder. On my setup (as I started with the 3 CD-ROMs) it's called C:\Program Files\Activision\Rome - Total War.
The original game came as 1.0. I patched it to 1.2. At that stage I took a copy of the folder and put it some where safe (another folder on the same PC). This copy is used as a base for any mods that use RTW 1.2 (RTR 6 Gold for instance). This is my 'clean install of RTW 1.2'.
I then installed RTW BI over the original folder and then took a copy of that folder (it's the 'RTW 1.5 RTW BI 1.6' folder shown above). This is my 'clean install of RTW 1.5 RTW BI 1.6'.
When I want to install a new mod I create a new folder and then copy the contents of the 'clean folder' into it. I then apply the mod to the new folder. The following are the folders I have at the moment;
When I first started playing RTW and it's mods I went through the uninstall / reinstall process several times. Someone pointed out the ability to take copies of folders which I have done ever since. The only time that I've had to install again is when I bought a new PC. I haven't had to uninstall the game since taking this approach.
This approach does use up disk space, if that is limited you can always take a copy of the folder and burn it onto CD-ROM (more than one) or DVD-ROM. A RTW 1.2 install takes about 2.28Gb and a RTW 1.5 RTW BI 1.6 takes 3.17Gb.
I keep all my games in separate folders. If I mess up the install of one it's simply a matter of deleting that folder and starting again by copying the clean base and then applying the mod.
The official patches will only install to the original folder name. Mods generally allow you to decide where you want them installed. The Mod will tell you where to install either in a readme in the download or on the web page.
The game folder means the folder under the Activision level.
The data folder means the folder called 'Data' inside the game folder.
What can be confusing is the many different versions of the RTW game there are out there. The way to work out which version of RTW you have is to launch the game and get into the options menu. On the top right hand side is the version number. This will usually be true of a mod as well but I have seen some mods overwrite this number.
The guide that shows some of the many versions of RTW out there can be found here (it's from the RTR forums):
http://www.twcenter.net/forums/showp...04&postcount=1