1 Get an external hard drive with a USB 2.0 connection. You need this connection to connect the drive to the console. Most recently manufactured hard drives should have this type of USB adapter included.
2 Format the hard drive to read FAT32 files. Using a Windows PC, create an FAT32 partition on the drive and format the volume. You'll need a program like Partition Magic to do this.
3 Load all the content you want from your PC onto the external drive. This should consist of photo files, MP3s and any other files that can be read on the Xbox hard drive.
4 Remove the external hard drive from your PC. Plug it into your Xbox 360 console through the USB port.
5 Go to the Media menu on your Xbox screen. Select "Portable Device" from the menu. All the readable files saved on the external drive should be available to read on your Xbox 360.
Read more: How to Use a Regular External Hard Drive on an Xbox 360 | eHow.com
How to Use a Regular External Hard Drive on an Xbox 360 | eHow.com