hi,
is there any utility like task manager in windows?
in which i can terminate processes in graphical mode.

Linux Archive

Just open a terminal window type top find the process you need to kill press k it will ask for the PID number enter that, press enter, then yes to confirm. Thats it

Here is a function I have in my .bash_profile:
psfind()
{
ps aux | grep -i "${1}" | grep -v grep
}

So if I wanted to kill firefox, I would just do:
psfind fire
then
kill (pid)

or, just type:
killall firefox

but even better is to just type:
xkill

as for graphical ones:
ksysguard
gnome system monitor http://freshmeat.net/projects/gnome-system-monitor/
gwcc http://gwcc.sourceforge.net/

I don't know what distro you're running, but chances are you already have the first two.

I use KDE System Guard when in KDE.
Else in a console:
ps -a to get the PID then do
kill -9 PID

htop is ideal for this. It's almost certainly available from your distro's repositories. It's an ncurses application so runs in the terminal but presents information graphically as well as textually and is easily controlled using the function keys (with clear indicators at the bottom of the screen as to which key does what). If you run Xfce it has its own task manager which is entirely graphical and will let you see resource useage and kill processes in the gui. If you simply want to kill a badly behaved gui application you can Alt+F2 and run xkill and do it with the mouse.

gnome-system-monitor in gnome