I don't see the need to convert forward slashes to back slashes.

With all the talk of APIs in this subthread I'd just like to remind everyone of the probably hundreds if not thousands of nodes on this site of people doing things like split /\\/, /\\([^\\]+)$/, and many more variations of hardcoded separators. Extrapolate that out to all the other programming languages and I think there is tons of non-portable code out there, therefore I personally always use the respective OSs' native format.