Mr wp100, you have been very helpful. And I guess I have no further questions. Just wanted to tell you that, I want to build this programmer because, if I use serial port of my computer, then I have to disconnect external LAN (and possibly other peripherals). In other words, serial port of my PC is really messed up as it absorbs more than usual amount of power from the supply.
Lastly, can you please tell me, whether this programmer can program both 5V and 3.3V devices or just 5V devices??