Not only is it likely or possible but definite.  Any partitions on your drive are visible if the right resources are installed on the OS you are using. 
If you can access the files from windoze then they can be taken by malware.  Only exception to this rule is to physically remove the drive for other OS, or to encrypt the other drive and have it "locked" while in Win-environment.
I usually store my keys on a jump drive.  That way if the drive isn't there neither is the file/access.


Good Luck
Glitch