Quote Originally Posted by PrOmETeO
Well, it's almost 2 months ago when i installed knoppix onto my laptop, and when i make an apt-get update , it sees too many sources, and i don't know if i can eraise some of them, like the testing ones, nor the unstable...

A lot of Thanks To make That distro rules!
You need to put a # character in front of the lines which are causing the file not found errors in the sources.list then apt-get update again and they should go away. This is what I use for the sources.list and it gets me everything I want your needs may differ.
Code:
# Security updates
deb http://security.debian.org/ stable/updates main contrib non-free
deb http://security.debian.org/ testing/updates main contrib non-free
#deb http://security.debian.org/ unstable/updates main contrib non-free

# Stable
deb http://ftp2.de.debian.org/debian/ stable main non-free contrib
deb http://non-us.debian.org/debian-non-US stable/non-US main contrib non-free

# Sources
deb-src http://ftp2.de.debian.org/debian/ stable main non-free contrib
deb-src http://non-us.debian.org/debian-non-US stable/non-US main contrib non-free

# Testing
deb http://ftp2.de.debian.org/debian/ testing main non-free contrib
deb http://nonus.debian.org/debian-non-US testing/non-US main contrib non-free

# Sources
deb-src http://ftp2.de.debian.org/debian testing main contrib non-free
deb-src http://nonus.debian.org/debian-non-US testing/non-US main contrib non-free

# Unstable
deb http://ftp2.de.debian.org/debian/ unstable main non-free contrib
deb http://nonus.debian.org/debian-non-US unstable/non-US main contrib non-free

# Sources
deb-src http://ftp2.de.debian.org/debian unstable main contrib non-free
deb-src http://nonus.debian.org/debian-non-US unstable/non-US main contrib non-free

## Various Multimedia Helper Apps Mplayer, Real, etc.. ##
#deb http://marillat.free.fr/ testing main
#deb http://marillat.free.fr/ unstable main
#deb http://hpisi.nerim.net/ unstable main
deb ftp://ftp.nerim.net/debian-marillat/ unstable main

## XFree 4.2/4.3
#deb http://people.debian.org/~branden/packages sid/i386/
#deb-src http://people.debian.org/~branden/packages sid/source/
#deb http://www.penguinppc.org/~daniels/sid/i386 ./
#deb-src http://www.penguinppc.org/~daniels/sid/source ./

## Expermential needed for XFree86 4.3 for the KDE 3.2
deb http://ftp.debian.org/debian ../project/experimental main contrib non-free

## K3b 0.10.1 sources for sarge requires KDE > 3.1.2 from SID
#deb http://www.planet-moll.de/debian sarge main

## Kio-apt sources for unstable provides apt:/ in Konqueror location bar
deb http://lpnotfr.free.fr/debian/ ./

## Java Runtime j2re1.4
#deb ftp://ntama.uni-mainz.de/pub/debian unofficial/

## KDE 3.2 built for unstable and 686 or better processor
#deb http://www.cs.uni-magdeburg.de/~aschultz/debian/ unstable/
deb http://rs.fuzz.nl/muesli/686/kde_head/ unstable/