I have been looking around the web but the more I find the more confused I get. What is the differents?
When I installed debian on my laptop I used the woody net install, and updated by changing my apt sources from stable to unstable and did apt-get dist-upgrade. This gave me kde 3.3 amongst other things.
When I installed debian on my stationary I used the first CD from debian sarge. This had the apt sources set to testing by default, and I got the system from the net this time to. This gave me kde 3.2.
From what I read testing is newer than unstable, so way did apt install an older version of kde when it was set to testing?
I also find that the second system I installed runs smother and faster. There are surely other reasons the preformans on the laptop is not good (at all). Like xfree eating my memory and CPU, I read that googeling for "xfree86 3dfx memory" would get me the answer, but it didn't so if someone more experienst than me could tell me what this means It would really help.

hmm

This is actually incorrect. Read on (I got this straight from Debian.org ):

stable
The “stable” distribution contains the latest officially released distribution of
Debian.
This is the production release of Debian, the one which we primarily
recommend using.
The current “stable” distribution of Debian GNU/Linux is version 3.0r3,
codenamed woody. It was released on October 26th, 2004.

testing
The “testing” distribution contains packages that haven't been accepted
into a “stable” release yet, but they are in the queue for that. The
main advantage of using this distribution is that it has more recent versions
of software, and the main disadvantage is that it's not completely tested
and has no official support from Debian security team.
See the Debian FAQ for more information on what is “testing” and how it
becomes “stable”.
The current “testing” distribution is sarge.

unstable
The “unstable” distribution is where active development of Debian
occurs. Generally, this distribution is run by developers and those who like
to live on the edge.
The “unstable” distribution is called sid.

And more from Debian.org:

release 3.0, a.k.a. the `stable' distribution
This is stable and well tested software, it changes if major security or
usability fixes are incorporated.

the `testing' distribution
This is where packages that will be released as the next `stable' are
placed; they've had some testing in unstable but they may not be
completely fit for release yet. This distribution is updated more often than
`stable', but not more often than `unstable'.

the `unstable' distribution
This is the version currently under development; it is updated continuously.
You can retrieve packages from the `unstable' archive on any Debian FTP
site and use them to upgrade your system at any time, but you may not
expect the system to be as usable or as stable as before - that's why it's
called `unstable'!

Hope this helps.