Installing PHP on 2nd Windows Drive

I got a preconfigured package - Apache 2.0/PHP/MySQL - up and running, then I installed Apache 1.3. Everything seems to be working fine, and I'm ready to start tweaking it. In the meantime, I bought a book about Apache, PHP and MySQL, which includes tutorials on downloading the programs individually. I don't want to mess up what I've already installed, but I have an external hard drive that I use for backing up my documents. Could I install new Apache, PHP and MySQL programs on that drive? They wouldn't interfere with the equivalent programs on the C drive, would they? In fact, is it possible to have PHP programs from two hard drives open at the same time? After all, I can open up documents on both drives with Windows Explorer. Of course, I guess I'd have to install Dreamweaver on the second drive, too, so I'd be able to test PHP and make sure it's working. Thanks.