Hi,
It's better and more reliable to have the disk set

There's allot of things that can go wrong with a download especially one that large,
Cheers.
Hogwash.
My downloads and my USB media have stood the test of time. My original Microsoft discs are all slowly wearing. When I initially bought the RTM version of XP x64, I made a copy of it that to this day performs better than the actual disc in terms of both speed and CRC issues.
I didn't even bother after I heard my Windows 7 disc skip once or twice. From now on I'll stick to downloads and alternative storage, thanks!
Hogwash. The iso downloads are often corrupt due to D/L speed, web traffic, server traffic etc. ThrashZone's statement is correct, and I've never heard a DVD skip.
I have an original w7 Student Upgrade disk for 5 years which is still perfect, no "skipping" or the like, works faster than the copy I made. USB sticks are faster though, but can get corrupt laying around as can an optical disk.
Yes MS does allow online keys to be delivered in the US, just not w7 now since they are pushing their other stuff down our throats.
Amazon.com: Microsoft Windows 8.1 Pro Pack (Win 8.1 to Win 8.1 Pro Upgrade) [Online Code]: Software