The buntus don't use su or su - but sudo. In other words, there isn't any "root" on a Buntu system. That doesn't mean that it isn't possible to set up a root password, though. You first log in with username and user password and then you type sudo passwd; you will be prompted for a root password. But there isn't any need to, just use sudo wherever you'd use su.

You can start xfce with startxfce4; if the system doesn't pick up from there, you put that in a hidden file in your home directory or you can log in through gdm (see /etc/X11/ for the display manager file).

ok i tried command "sudo startx" still asks for a password so i put in either blank or my pass won't let me in

That is puzzling. Are you sure that you are using the same password that you set for your user during install?

Did you install GRUB? Not that it has anything to with your issue, but it will provide a way out if this password issue can't be solved.

well if i can log in doesn't that mean i use the same pass? and i installed grub. can i just start directly to X ?

You can't start x from grub (not to my knowledge as least) but you can set a password by telling grub to boot into single mode. Just append
single
to the line that goes kernel /vmlinuz etc.
When you get a terminal, type passwd and it will prompt you for a root password.

Oh, by the way, have you tried a simple startxfce4 instead of sudo startx?

i actually got to the sudo working (yaya) but... I start the x server and all i see is a gray screen and the command line takes 1/4 of the screen and that's it ...

That means you aren't running xfce yet. That can mean two things: either you xfce wasn't installed - but I have no reason to think that it wasn't - or you need to start x with startxfce4.

so:

Boot up
Log in
and "sudo startxfce4"
put in password and it should work?

ok in case there is no xfce installed what do i do?

ok when i try startxfce4 says command not found :/

OK, let's try and start a log-in screen:

/etc/init.d/gdm start

If gmd is not installed:
sudo apt-get install gdm
then
/etc/init.d/gdm start

You could also select xdm instead; it's a lightweight in comparison but it has more limitations too.

If only a minimal system was installed by mistake:
sudo apt-get install xubuntu-desktop
or if you need just the window manager
sudo apt-get install xfce4.

I'd say, give each a try. You appear to have xorg so it's probably just a matter of getting the log-in manager to launch. Going by the error you got, xfce4 may not be installed yet either. With a luck ,the first one or two commands should do the trick.

now i think it is going crazy...
i tried the first one said it is not there
tried installing asks for cd and never detects it
tried installing xubuntu failes
tried installing xfce4 failed

is there anything else i can do?

or is there a way to install from the normal CD without using the live CD cuz it freezes every time when i reach 54%

I'm getting a bit confused now. You mention the livecd but in your previous post you said you used the alternate cd. So which one did you really use to install? I believe that the livecd requires at least 192MB of RAM so that might account for any freezes.

Anyway, the reason that you are asked for the cd is because Xubuntu is set to install its basic stuff from the cd but although that option can be uncommented so that it installs everything from the repositories instead. Now it is quite possible that the cd doesn't have gdm - it is the gnome display manager after all and Xubuntu may have only xdm. In that case you should do:

sudo /etc/init.d/xdm start

Before doing this, it may be a good idea to do a little investigation. Check the output of whereis xdm
and
ps ax | grep xdm
If the latter returns anything at all, xdm is already running; if the first one returns a set of paths, you know that it is at least installed, whether it is running or not.

Let me explain i used the alternate CD because during the live cd it always froze exactly at 54%. but it worked ok as a live cd just the install failed so i'm asking is there a way to install using the livecd cd without actually running the session (use a command to directly without a live cd session). Or is it possible to install it via another computer (network install somehow?

Well, I'm not so sure about the latest versions but it definitely was possible to install without a GUI running. It seems to me that this option was removed, however, and that it has been replaced with the standalone alternate installer.

I'm not aware of any option to do a network install. But even if it were, you'd be doing essentially the same as using the alternate cd. It seems very likely that you'd still end up with a command line instead of a GUI.

But this should help:
Log in from the command line as your user (and without using sudo!), list the contents of your home directory:

ls -al

Check whether you have a .xinitrc file.
If yes, do:
echo "exec xfce4-session" >> ./.xinitrc

If not, do:
echo "#! /usr/bin/env bash" >> ./.xinitrc
echo "exec xfce4-session" >> ./.xinitrc
chmod +x ./.xinitrc

Log out and back in. If it doesn't work, you have either a video problem (unlikely since the livecd appears to work) or you already have a display manager running.

ok i lost my faith... Anybody knows a good linux distro that uses some kind of graphical environment and will work on an older machine? (one that is still supported not like ubuntu 5.10)