This particular mod is not directly related to XBMC, but will defintely upgrade your overall modded Xbox experience. The stock Xbox hard drive is only 8GB, which doesn't leave much room for adding Xbox games, emulators, roms, music, movies, videos, pictures, applications, and anything else you'd want to store on the Xbox itself. Adding a bigger hard drive is easy, and almost essential. Any IDE hard drive that can be "locked" in hardware will do the trick. To find out which ones will work, look here. Almost any Seagate will work, which is what I'd recommend. I am using this Seagate 250 GB Hard Drive.
To accomplish this mod, you need:
- A modded Xbox
- Torx screwdrivers/drill (gauges 5,10,20)
- A hard drive
- Xboxhdm software
- A PC supporting IDE drives
- A router
The basic procedure is:
1. Backup your eeprom to a file (eeprom.bin)
2. Transfer your Xbox C Drive (and E if nec.) to a PC via ftp
3. Use Xboxhdm to make a bootable linux iso CD
4. Open your PC and disconnect your existing hard drives
5. Connect only your new Xbox hard drive
6. Boot from the CD
7. Format the hard drive, then reboot to CD again
8. Lock the hard drive
9. Open your Xbox using Torx screwdrivers
10. Remove old hard drive, install new one
11. Close up the case and boot the Xbox
12. Hook you PC's hard drive(s) back up and boot
Rather than list the steps myself in detail, here is a great tutorial from Scenyx. There are many other tutorials out there, too. Good luck.