Ah, the wonders of the 24 hour forum - you beat me to it picaxester! Yes, you can turn things on and off with vb.net. You need to write some code for the picaxe, download it, and set that code to listen to a different pin to the download pin (any input pin really), using serin. Then you send a byte or two from vb.net. The tricky bit is plugging back and forth between programming and talking to the picaxe and remembering which one you are doing. Ideally copy working code, or be pretty sure that it is debugged first.