I have a question about my new drive.

Hello, I just installed a new hard drive, a 1 TB WD Caviar Blue.
I formatted it and everything, and it has become my E: Drive. But the Hard Drive I already had is a pretty bad drive. I have windows 7 installed on it, but I am in the process of downloading and installing w7 again. I want to keep my first hard drive intact so that I can transfer all of my files onto my second drive after I install the OS. The thing I am worried about is that my new drive will remain the E: drive and maybe a problem would come out of this. Any idea how I could switch the drive volumes so that my new one would be C:?