The performance was so bad that after a day I thought that staying wired for such backups was not such a bad idea after all. You really need to test "How long will this take?" on wifi, lan, USB 2.0 and eSATA then see if you have the patience for it.
If I understand correctly, I can add an external hard drive to my computer and using the appropriate backup software, create a disk image. This will back up my OS, my data, files and programs, everything. Then if the computer hard drive dies, I can replace it with a new one and install everything from the backup.
I have a wireless network at home serving 4 computers. Can I do the same thing as above using wireless network storage?