How to clone a neighborhood
If you want to play a neighborhood, but you don't want to mess up one of the original three, you CAN make a copy of a neighborhood.
First create a new folder in the neighborhood folder with the new number, for example; N004. Then copy the files from the neighborhood you want to clone and paste it into the new folder.
To make a copy of Pleasantview, for example, copy everything in "My Documents\EA Games\The Sims 2\Neighborhoods\N001" to "My Documents\EA Games\The Sims 2\Neighborhoods\N004". (first unused neighborhood)
The files in a neighborhood directory have the neighborhood number in the filename so a rename the files will be necessary.
Open a command prompt window (You access it (in WinXP) through Start Menu -- > Programs -- > Accessories -- > Command Prompt) and change directory to "My Documents\EA Games\The Sims 2\Neighborhoods\N004". The main N004 directory and all subdirectories (Characters, Thumbnails, and Lots) run the following DOS command from the command line to change the filenames.
ren N001* N004*
(Don't forget the asterisks or it won't work.)
Start up the game. You will be able to click on the arrow to go to a second page of neighborhoods and your new neighborhood will be there and it will be called Pleasantview. Click on the name of the Neighborhood and enter a new name. Press ENTER to save the name. I had to go back to the original Pleasantview because the game does not allow duplicate names and rename it from Pleasantview0 to Pleasantview.
All your Sims will be intact, including relationships and family, they will not have their ages damaged or mucked with, and the new neighborhood will be indistinguishable from the original (until you play it). The Sims are distinct and different, like with neighborhoods in Sims 1.
If you want to start a fresh neighborhood (like for a Legacy Challenge) open up the cheat window (Ctrl + Shift + C) and type: deleteAllCharacters (Warning! This will delete *everyone*, so do this *before* you create your Legacy family).
You can make as many copies of a neighborhood as you desire and never spoil the original one.
The "master copy" of the neighborhoods are stored in this directory:
Program Files\EA GAMES\The Sims 2\TSData\Res\UserData\Neighborhoods
N001 = Pleasantview
N002 = Strangetown
N003 = Veronaville
If you delete the corresponding directory from your My Documents directory and copy the one from the Program Files directory, that should restore the original neighborhood.