Hi,
I'm glad that there is someone who has C64 too, great computer, especiall I loved creatures 2
You are right, that used basic, but nowadays things are different.
Good compiler for C/C++ is hard to chose. You can go to Borland C builder or MS Visual C or some GCC or whatever; I'd advise you to try good old BORLAND C 3.1 or 3.0; it is small, fast, with easy user interface; it has also good help with easy examples.
The choice if 21 days book for quick overview is good but I'd also advice you to get some serious reference.
Regards,
least