There's nothing about a file being on a Windows box that makes it already vulnerable. Every OS is pwn-able. It's not impossible to lock a Windows box down to be sufficiently secure in most scenarios.
There may be some benefits to using a live CD in certain scenarios for certain data. However, without knowing what data you are dealing with, how you intend to access it, and who might be trying to improperly access it, it is really impossible to answer scottp99
"Padre, nobody said war was fun now bowl!" - Sherman T Potter