As noted previously, the msvcrt.dll got the state of a system library and is thus included in systems from XP up. On earlier systems you will have to have a particular service pack level or get the redistributable package with the suitable version of msvcrt.dll.
But be careful. I noticed that the build target system will define whether a newer functions in msvcrt.dll will be used. For example functions involved in exception handling. Several of these aren’t available in previous versions of Windows and thus the built binary will really only run on the target and later. Previously it was possible to target binaries for – say – Windows 2003 Server and yet be able to run it on earlier systems.
// Oliver