Just to clarify something, all Vista DVD's have all versions on them. Your product key will determine which version you are allowed to install.
Spherrod is correct about the n versions. Unless you live in Europe, you can ignore the n versions as if they do not even exist. Even the Europeans rarely buy and use the n versions of Windows. There are two other versions of Windows you can ignore. The enterprise version is only for large companies who buy volume licensing and the Starter version is only available in poor countries.
That leaves just four versions to worry about for most people.
1. Home Basic
2. Home Premium
3. Business
4. Ultimate
Out of those four the most popular with home users is Home Premium.