As Thef0rce noted, C and C++ aren't terribly far apart. In fact, all C code is valid C++ code. C++ is a superset (extension) of C to give it more object oriented support.
It's worth noting, on the topic of object oriented programming, that it is the program you write, rather than the language you use, that can be object oriented. Certainly, C++ makes that easier than C does, but it is possible to write an "object oriented C program".
On the topic of gaming- which is your point, after all- either one will work just fine. If you have already begun learning C++, I would stick with that. Personally, if I had the choice, that is what I would use any way (and I have used both languages, though not for games).
I would be interested in seeing the article that you just read, if it is on the web. I am guessing that it sites less overhead in the C language as allowing it to be faster code. Technically, this is the case, but these days, if you write decent C++, it won't make a whole lot of difference (computers aren't getting any slower
Also of note, Windows APIs are all written to conform with C. This means that if you use C++ there may be some C practices you will have to adopt to interface with the WinAPI. This is nothing to worry about though, and as I have said, all C is compatible with C++, so you won't have any compatibility issues with writing games for windows. If, of course, you are going to write console games (which is proly the best place to start), this won't be an issue.