I am a vc++ developer (but like Qt) interested in learning from open source project by contributing and reading the code. I use windows as primary development platform. Whic
I don't think anyone here can really answer the question "Which project will be right for me to start?" as no one here really knows who you are. Programming is an absolutely HUGE area, you can do low level systems code (i.e. drivers & OSs), databasing, web browsers, games, word processing, and the list goes on.
What you should do, is find something you would like to work on, and start playing around with the code. Try out several different projects in that area and see what you can understand, contribute to and learn from (its also a good way of seeing a variety of some of the programming paradigms out there). Also, if you are trying to learn from this as well, you should check out how much help and communication between the members of the project there are and how much they seem to be willing to help one another (and if there is almost no communication, i'd worry about the project surviving much longer anyway).