I have personally bought from
http://www.system-mods.com. I used a Xecuter 2.3 pro. It comes with an external switch that you need to turn the chip on. I lost it and they shipped me another at no cost.
Try to get a xbox with a samsung drive. That will save you a lot of headaches. I find all I really use is a hard drive loader, a file manager, XBMC or whatever, and a dongle-free DVD player, and evox of course. Check out Slayer's evox installer, it has all you need.
BTW, do a google site search for this stuff, type in google "site:www.xbox-scene.com <whatever>"
