i bought mine from amazon. and i waited until i was ready to use it to install it.
there's a 180-day clock, and that way it might just be easier having the disk and using it when you're ready. don't install it before that to check it out.
Its the same whether you order it from Amazon on CD or download it so just get it where its cheapest. If you need it immediately, then download it. Ordering the CD will take a week or two. The Amazon price seems to fluctuate - sometimes its cheaper at Amazon, sometimes its cheaper directly from scholarware.
