"2) I´m confused, should I get started wuith QBasic, or C? I don´t know oop (object oriented programming)"

C does not require knowledge of OOP. The choice between QBASIC and C is yours to make, depending on your criteria. Are you more familiar with one versus the other? For what it's worth, I did go ahead and put some dumb-as-a-stump Win32 compatible C routines in my 8052.com User space http://www.8052.com/users/dhenry that you can embellish if you choose to use C.

Your code has me wondering -- after reset, the code jumps to START, which then enables interrupts and goes into a tight spin-loop without having configured the serial port and timer baud rate generation to be able to transmit or receive. The serial port and timer initialization code is in the ISR. How will this initialization code ever get executed? Just something to think about...