Buy the download from Amazon, and save a copy of it to DVD, flash drive, or some such so you've got a separate copy if something crashes. After it's installed you don't need the installation disk/program.
OTOH having a USB DVD drive is pretty handy to have and the program was selling for around $31 for the DVD. USB DVD drives can be had for around $15, but not from an S&B store.
It's unlikely that Street Atlas maps will be much different next year from this year. I usually buy a new copy every other year. It's a waste of money to buy a new copy every year IMO.