I finally purchased PTW, but am in the latter stages of a very enjoyable Civ III game. I have downloaded some mods, such as Snoopy's terrain mod. My question is this: if I install PTW, will I lose the ability to play that saved game? I don't see this covered in the manual. Thanks in advance.

Once you install PTW, you have the option of playing either "Vanilla" Civ3, or PTW. It just depends on which CD you put in the drive. So you can play your saved games either as Civ3, or open them in PTW and automatically convert them to PTW format.

Graphics mods installed for Civ3 are the default graphics used in PTW. So, if you are using snoopy's, that is what you will see in PTW. :D

What is the definition of Vanilla civ? I have search woth no luck.

I have play the world, so does this mean I have Vanilla civ also?

Vanilla Civ3 is the non-PTW version. The old 1.29f (patched) version.