Installing without a disk

Hello all.

I have two boxed copies of Windows 7 Home Premium (or did, until I mislaid one)and both are currently installed as 32bit versions on 2 different PC's on my network.

I intended to move over to 64bit on one of them, but I cannot for the life of me find out what I've done with the blasted disks (or the box for that matter). I have the product key written down from when I installed it, and have verified its accuracy by using "Produkey" on the current 32bit installation.

Does it matter if I use the other disk to carry out the installation? I'm hoping that the disks are just disks and that it is the product key that matters.

Box boxed copies came with 2 disks, one with 32bit and one with 64bit Windows.

I intend to format the disk that currently has 32bit Windows on it, install 64bit and then activate it using the same product key. My understanding is that doing that is OK. I'm just a bit worried about the product key being hard coded onto the disk. I had that problem with an XP upgrade disk a few years ago.

I downloaded an ISO last night but have discovered that I don't have any blank DVD's

Thanks for the replies :)

So just to clarify, I do not have a large enough flash drive, and I do not have any blank DVD's. So using an ISO is out of the question for today. So if I want to carry out this installation today, am I OK to use the installation disk from the boxed copy that I haven't lost? The installation will accept the product key that belongs to the DVD that I cannot find?

That's brilliant, thanks for the rapid repleis. My problem has been solved :)

Just out of pure curiosity, am I right in thinking that I can't boot between 64bit and 32bit on the same PC using just the one product key?

Not that I intend to do that, but I am curious. I have a PC that has XP 32bit, Windows 7 32bit, and Windows 8 32bit on it, but all of those have their own unique product keys.