xemu: Original Xbox Emulator - YouTube
since the retroarch menu doesn't work on the ps2 bios, you need to update the bios to enable it. do this by finding the ps2_bios.xml file and copying it to the x:/windowsapps/[long retroarch folder name]/system/pcsx2/bios folder on your xbox. at this point, if you've gone through the ps2 bios guide, you'll need to update your bios by putting it into your ps2 drive and booting your console. if you get any errors, check out this guide.
download bios xbox 360 emulator 3.2.4
now that you have the bios file, we need to get the rom for the game you want to use. once you have this, edit the xml file to insert the rom into the playlist and click save. this will be your first rom!
now we need to find the emulator we want to use. currently, there are a few good emulators out there, but i like retroarch . you can check it out if you're interested in this type of thing, but you should know that it's definitely in alpha, and is lacking many features like various game flags or hard disk installs. however, it's free, open source, and is very easy to use.
if you go to the retroarch wiki , you should be able to find good information on how to set it up. once you have that installed and have played some games, you can apply those settings to other games, but for now, just set it up to run at 640x480 and show text in the menu. you should be all set!
to get started, you will need: 1) 1 - 3 gb of free space on your hard drive, 2) windows 10, 8, 7, or windows xp home edition (although you can run the emulator on other versions as well, and it will just not look as pretty). of course, this is assuming you have a bootable usb drive of some sort. i recommend the sandisk extreme portable usb key ($9.95) , and a charger for it. all that being said, if you have a usb 3.0 or higher port, you can also use the hyperx usb 3.0 adapter ($19.99) since it has usb 3.0 on the other end.