Question: Where would the physical files be?

Answer: 
It depends on the OS and whether or not roaming user profiles are enabled.

For example, on XP, with non-roaming profiles, the location is

```
<SYSTEMDRIVE>\Documents and Settings\<user>\Local Settings\Application Data\Microsoft\IsolatedStorage 

```

On Vista with roaming profile storage,

```
<SYSTEMDRIVE>\Users\<user>\AppData\Roaming\Microsoft\IsolatedStorage

```

See an [Introduction to Isolated Storage](http://msdn.microsoft.com/en-us/library/3ak841sy.aspx) for more info.
Location differs per `IsolationStorage` scope

```
Local user     [LocalApplicationData]\IsolatedStorage
Roaming user   [ApplicationData]\IsolatedStorage
Machine        [CommonApplicationData]\IsolatedStorage

```

The folders can be retrieved by `Environment.GetFolderPath` method.

Windows 2016 has it like this

```
Local user     C:\Users\<user>\AppData\Local\IsolatedStorage
Roaming user   C:\Users\<user>\AppData\Roaming\IsolatedStorage
Machine        C:\ProgramData\IsolatedStorage

```

More details can be found [here](http://www.albahari.com/nutshell/IsolatedStorage.pdf).