Note that these instructions completely wipe your USB harddrive, and consider it to have no formatted filesystems. If you follow these instructions, you'll completely delete the contents of your external USB harddrive

Turn the drive's power on, then plug it into your USB adapter.
After plugging it in, and you type tail /var/log/messages you should have an entry that says something like:

kernel: Attached scsi disk sda at scsi1, channel 0, id 0, lun 0

Make note of the device (sda in my case), as you'll want to use this device when you partition and format the drive.

Next you want to create your partition on the new drive with the fdisk command:

fdisk /dev/sda (replace /dev/sda with your actual USB device)
Press p and you should see a list of the current partitions on the drive (should be empty, if it's a new drive)
Press n This creates a new partition

At this point you will be asked for the starting and ending sector you want to use for the partition, if you want just one big partition, simply select the defaults

Once you have your partition created, you can press p again to view your partition. If it looks good, you can press w to write the partition to the drive and exit the fdisk utility.

Now that you have your external USB drive partitioned, you can create the filesystem on it with the following command:

mkfs.ext3 /dev/sda1

Now add this to your /etc/fstab
/dev/sda1 /mnt/usbdrive auto user,noauto 0 0

Make the directory for the usbdrive to mount on:
mkdir /mnt/usbdrive

Mount all the devices in the /etc/fstab:
mount /mnt/usbdrive

Done.