Is the Remote Access Connection Manager service and Remote Access Auto Connection Manager, running in the background of Windows 2000, really necessary?

the auto connection manager you can disable safely to prevent auto-dial; the connection manager should not be disabled unless you don't connect to ANY network at all (including internet)

I disabled them both, including their dependancy the Telephony service, and my home network and internet connection work just fine.

Sorry Chief, but what you are saying is impossible. Windows cannot perform a Task without the Service that Task depends on. It really is that simple. It CANNOT. There is no way around this, not for you - not for me - not for anyone. M$ made it so. I hold the MCSE certification so I feel qualified to say this.

Bottom line:

If your internet connection is working, then the services you mention are running, regardless of what you have done. It cannot work without them.

I highly recommend advanced users obtain the MCSE Training kits that are available even if you do not intend on gaining the qualification. There is much knowledge that could be of use to performance seekers, many of the commonly known XP tweaks originate from the Windows 2000 kit.