DinohScene was more saying that custom parts like that tend not to be stocked by the digikey/farnell/element14/... or even on ebay all that much, as you have seemingly found out yourself. If you do want to fix a falcon motherboard though (why I don't know, especially as I don't see any evidence of JTAG or RGH installs on that, but to each their own) then you should be able to find a previously red ringed falcon motherboard* or whole console (presumably without power, controls, video, possibly DVD...) and cannibalise that for the parts instead -- often the best source for parts is another broken example of the same device. Red ringed consoles go for next to nothing and if you ask at a game shop selling second hand things or anywhere you can find second hand 360s you can probably pick one up and have someone thank you for freeing up the space, and you need not worry about red ring or some other failure as you presumably only want the USB ports from it.
*I don't know if that would have changed between revisions of original xbox. I can probably have a look from the examples I have here later if you really want.
If push comes to shove then USB is USB is USB so you might not be able to have it sit nicely in the housing but if you just want to have something plug in to the charge or something then you can instead fly a wire to whatever USB socket you can get or scavenge from something else.