[newbie alert] system configuration

I have a Wintel box at home upon which I have installed Cald OL 2.3, the
WHOLE thing. I want to teach myself basically three things:

NFS server
Web Server
Mail Server

I want to do this to help my wife in her computer consulting business in
case she runs across a Linux system or a client needs more information or an
installation. I have a 10 gb HD on the system and Linux was installed on a
single partition. In order to use these things individually, do I need
three separate partitions, one for each "server" or can I learn and run
everything the way it's installed now?

I will be using both Windows and Linux as clients (another windows computer
and a Linux-based laptop) on our home network...so much to learn I don't
know where to start.

Tim