"To be honest, the main reason I'm doing this is because a lot of the software I'm going to run on the server doesn't allow it to be ran on a server OS. Why is beyond me. But I still need to run it, and I can't run it on my computer as it takes up way too much RAM."
That is strange. Unless there is a licensing issue, it should run just fine on 2008R2 if it runs on Windows 7 (they are built on the same kernel).
"I've never actually made a dvd or CD for drivers, so I don't know how to."
It's nothing special - the same any CD with data files. Download the driver at the link I gave you, run it to extract the contents, then copy/burn the extracted files to CD. USB would be recommended though.
"I configured it myself, sorry for the misunderstanding."
No, that's fine ... just wanted to make sure. I've seen several issues where people just tried to install/run on the existing array, experiencing odd problems, and the corrupt array may have been the reason it was originally decommissioned.
"So essentially, it just becomes a plain computer at this point?"
Right. But depending on how critical this system will be, the systems management software may be a big reason to go with a Server OS. Without it, you will not be able to see the hardware log or do any system maintenance/monitoring/troubleshooting from the OS - it will require a reboot, minimum. If it isn't that critical of a system, then maybe you don't need it.