They told you?
And yet here you are, not fine, because you actually have optical discs that you need to read. I presume you knew this when you were buying your new system.
I really hope you manage to download that gigabyte+ of data successfully and get it installed, but seriously, ask yourself: How much money are you saving by not buying a $79 optional EXTERNAL USB SuperDrive vs. how much time are you wasting screwing around with this?
-Noel