Hawkeye22 has there a poin again.
You can download the ISO image, you need a virtual drive for it.
Try MagicISO or Alcohol52 or Alcohol120 and many more.
Microsoft has one too if you like.
However, it might be that your true license key will not be accepted.
So, you have to try.
I don't know where, but you could start the search on the net if you like. And you don't have to look for an ISO, an installation version .exe could do it too.
I would try to copy the files ad a friends (or where ever) pc with a drive and send it by email as an attachment to your own email address. You can download it from there to your computer. Yahoo has an attachment option for bigger files that might be put in parts before. You can use 7Zip for it, it can Zip it in more parts. Don't use self extracting, the email website, Firewall and/or Anti-Virus software might block it.
You can do this with an ISO file too, when I'm not misstaken.
So, no matter what you choos, you can retrieve it ad your own comuter.
Good luck & have fun doing it!
Happy Hollydays & Best Wishes 2013!