You can find this little gem here. I know that we're all supposed to know how to correctly setup a solution and I know that we all have our way (and reasoning) for how we set it up. It would be nice to come up with a standard way to do this. Tree Surgeon to the rescue. This is not a tool you will use everyday, but it will become invaluable when you do.
The basics are just that. Fire up the tree surgeion GUI and point it to the directory where you want your solution set up. Give your solution a name and let it do the rest... It even builds a working NAnt build file with recommended build configurations.
For the NAnt newbies, this will help tremendously. For the rest, it never hurts to have an automated head start.