Nevermind, I figured it out. The documentation says this, so that's why I went with <iostreams>
Code:
useoldio.h
/*
* Warning C4995, '_OLD_IOSTREAMS_ARE_DEPRECATED' is a deprecated name, is
* being issued because the old I/O Streams headers iostreams.h et al will no
* longer be supported from VC8. Replace references such as #include
* <iostreams.h> with #include <iostreams>, using the new, more conformant, I/O
* Streams headers.
*/
I used <iostream> and the warning went away.