Okay, wow. I have finished the whole software side, Mame and an FE and what roms I want, now I actually have to build the thing. I figured the joysticks and buttons might take a while to layout and construct a control panel and that I might as well just get some light guns so I could at least enjoy some sweet Zombie Raid, Area 51, Jurassic Park action while building the rest. I didn't think even the guns were this difficult.
There should be a sticky of peoples light gun setups and experiences. Perhaps someone should start a Foundation For the Betterment of PC Arcade Guns (FFBPCAG) that would endlessly research a solution to all of this.