Yes, but consider a change needing to be made down the line:

Q: "Hey petdance we're porting this script to Unix, can you make it run there too?"

A: "Sure, I'll just change the constant."

Q: "Hey what did you change in that script so that now it doesn't work on NT anymore?"

A: "Hmmmmm"

Ok, so the example is a stretch, but imagine the solution using a sub instead of a constant.

sub LINKS {
    if (sub_to_determine_OS() =~ /(Unix|Linux)/) {
        return "/u/jreades/links.txt";
    } else {
        return "U:\jreades\nt_links.txt";
    }
}
[download]

And all of that requires exactly no changes to the rest of your application.

Yes, it is paranoid, but that doesn't mean they're not out to get you.