I think you might do better with one of the ARM development boards.

I got one for my plasma cutter. It has a little touch screen, USB, serial, memory card socket to plug in GigaBytes of extra memory , buttons, LED's and a squeaker all powered off the USB cable.

TI even have a stepper driver dev board with all the bells and whistles plus sample code. List is £80 but someone will sell them cheap eventually.

The GNU compiler is free, gives unfettered access and runs under Windows.