Automatic Backups through usb

I’ve just lost the HD on my Toshiba again and, just like last time I dropped the ball on keeping up with my backups (this time, 1 yr old). My son runs a Mac and has an external drive called Verbatim where he keeps a constant update on all his files. Is there anything available like that for Windows? Just a simple USB connection? I know I can use an occasional external HD like Maxtor, I have one but, I don’t know if it backs up everything and I’ve got to remember to plug it in occasionally and not once a year as before.