knoppix 3.3 hard drive install utilized knoppix-installer, debian version.

Running apt-get update has about 95 sources it checks, what can I "safely" remove from apt-get/sources to get a minimal source list, and not break my system? When I run it, i seem to get a mixtuer of stable/unstable/testing...is this required? or can I go with just unstable...etc.etc.etc.

Thanks
TheBman