At the moment, if you want to work for a company or clients, your best bet is to learn one of the two big "ecosystems": Java or .NET. Most of the jobs you'll see posted are in one or the other. And, most of the people working those jobs don't know any C/C++ any more.
If you just want to learn to program for the sake of learning how to do it, or for your own startup company/project, I'd go with one of the more "modern" languages like Python or Ruby. If you're looking to learn to speed your sysadmin tasks up, Perl or a shell scripting language (including the newish Windows Powershell) might fit the bill better.