C++ is a
language. you don't just download it. with C++ you write source code in .cpp format, and a program called a compiler makes it into an executable file (there's a little more to it, but that's all you need to know for now). it is more complicated than darnbasic, but if you can understand it, you will understand darkbasic more and be closer to a career in programming. after C++, you then need to learn about the different APIs (application programming interfaces), SDKs (software development kits), and libraries (such as Win32). so my advice is- go ahead. it's worth it. as for making the ultimate game, hold your horses for a second. if you practice you can make smaller to really decent games, better with more experience. get a job for a game development company, then you can go for the ultimate game, but keep your dreams and ideas in mind, just realistically. just read, read, read, find some tutorials, practice, practice, practice, practice, practice, practice, get some enthusiasm for it, practice, practice. and maybe practice some more.
good luck.