Sunlite also makes interfaces/software that you might want to check out, as well as Chamsys. The Chamsys software is free, but it's hard to find their interfaces (if you find a reputable site, let me know...).
It just occurred to me, that having the USB to DMXadapter may not really solve the idea you have. You ant your sound and lights to be able to be cued simultaneously, so that would require either two pieces of software that can talk to eachother, one for lights and one for sound or one software to control them all. I have no knowledge of either of those exist.
So, I ask, do you already have a lighting console and are you just trying to find something to use in it's place or are you starting from scratch? If you have a console already an easier route to take may be MIDI Show control. Most consoles these days support MSC and if you use a program like SFX for your sound you can just like the sound computer and lighting console via MIDI.