In my experience (which is as biased as everyone else here giving advice) your Fortran and COBOL are worthless, if not a little dangerous because the functional programming paradigm runs counter to object oriented programming, Model-View-Controller design patterns, etc. The assembly experience is, on the other hand, valuable because so few of these kids coming into the job market really understand the difference between a stack and a heap, understand what a pointer really is, etc.
In other words, the degree by which your lower-level language experience can give you an inherently deeper understanding of what's going on in higher-level languages may be your saving grace.
If I were to offer a programming language of choice for you, it would actually be Objective-C. (Thus, I would tell you to target iOS for learning your first platform.) It is the simplest superset of C you can find, and it has strong origins to the 1980's, and thus may seem the most familiar/comfortable to you. Given your description of your experience and background, you might be well suited to follow the (free) Stanford iPhone/iPod Touch development course that's available from the "iTunes U" section of the Apple iTunes Music Store. That's an undergrad level course aimed at developing Objective-C and getting started in that environment. And it's FREE.
One last piece of advice to get your head around: make it your mission to write GOOD, ELEGANT code and not prolific code. If I were interviewing you for a job, hearing about hundreds-of-thousands of lines of code would give me the most hesitation. Less is more, and I would want a person who spent 80% of his time thinking about how he was going to solve a problem and 20% of the time doing the implementation. My own experience working with Fortran programmers (in the 90's) was that they rarely understood this, and often wrote GIGO.