the only thing I can add is that the home built interfaces are 100% compatible with the software... not all PC's will want to find the interface, but thats not an interface compatibility issue. 9 out of 10 times its a problem with other devices (palm pilots, etc) ,or their software rather, accupying the interfaces com port. On rare occassions, some PCs (mostly laptops) com ports don't supply enough voltage for the interface to work properly without modifying the circuit slightly. When I say rare, I mean really rare. I've made a whole lot of these (several hundred) and I've only had one that this was thought to be the problem. The rest, every single one of them to my knowledge, work just fine. So are they really 100% compatible... yes, they are. Just make sure your pc is configured correctly.