Question: Where would the physical files be?

Answer: 
On my XP workstation I found it under c:\Documents and Settings\\Local Settings\Application Data\Microsoft\Silverlight\is\XXXXXXXXXXXXX
Where xxxxxxxx appears to be a random directory name. (under that if you wander around enough you should find the store for your particular app...)
When accessed/created by a system account, I found the folder here:

```
C:\Windows\SysWOW64\config\systemprofile\AppData\Local\IsolatedStorage

```