If you don't have any other programming languages before you then I'd start with C#. It's perhaps less intuitive to start with than VB, but it's syntax is much closer to real money languages of C#, Java, Javascript, C++ and C than the older and less industrially used VB, VB.Net, BASIC and so on. C# is also the preferred language at most companies I've seen (including Microsoft), so if it's jobs or money you want at the end, I'd go with C#.

Also you'll find pretty quickly that there's more and better examples and documentation out there for C# than there is for VB.

Ultimately if you're just programming for fun, it doesn't matter which one you use.

Also 40 isn't past your prime. A lot of the Windows kernel developers are about 40 (not all, but many of them), and they're the best in their field.