Vista Virtual Store

When using file or registry API, is there any way to know if the file or
registry operation will be done or has been done in the Virtual Store
instead of its original location ?

For example, my application is using file locations given by users. Some of
them maybe use "Program Files" subdirectories or other protected
directories. It will probaly work fine with virtualization but how can I at
least log the fact that Virtual Store has been used ?

Thanks for ideas.

Yanou