Well believe it or not; but I have run into a few situations with RH8 KDE where a few programs stop responding.
Is there something like Ctrl + Alt + Del to Task Manager to shut down the non responding programs?
Otherwise I will have to continue rebooting the old fashioned way when these things happen.

if you use kde, the easiest way is to hit [ctrl]+[esc] (default binding) that will bring up a dialog with a list of running processes.

however, I suggest you become aquainted with the ps and kill commands at the command line.

to see a list of all the running processes on your system, type:

ps -aux

I suggest you pipe it to the more or less command so you can scroll through it:

ps -aux | more

or

ps -aux | less

you can then find the pid of the program that will not stop correctly, e.g.:

alittle 29593 0.0 1.4 24256 7460 ? S Jul23 0:06 evolution

the italicized number is the pid, the bold name is the name of the process. with this number, you can then use kill to kill it. I'd start with kill [pid]:

kill 29593

if that doesn't kill it, you can try using the -9 option, which basically murders the program (don't do it this way if possible, it doesn't clean up any settings or temp files if you do):

kill -9 29593

it's actually not as complex as it may seem

put an icon on the desktop that executes
xkill

The crosshairs should give an idea what it does.

RO

Well, you don't need to reboot even if all of X hangs. Ctrl-Alt-Backspace kills X and everything under it, without rebooting.

you can also do alt+f2 then type 'ksysguard' on the 'Run' Dialog, afterwhich it will show you something synonymous to Windows' Task manager and you can already select which process to kill,

On the other hand, I was wondering if there's such thing in Solaris as Ctrl-alt-del function, I don't seem to see anything like it in it's /etc/inittab file...

kill -9 <pid>

If the computer is not responding, how are you supposed to open a terminal and type loads of commands?

The main short cuts you need are (by default):
Ctrl+Esc - Opens the task manager;
Ctrl+Alt+Esc - Launches Xkill. Press these keys then a single click on any part of the crashed window will instantly remove it;
Ctrl+Alt+Backspace - Restarts the X server. Can be used if both the above fail.

I completely agree with this.

I agree with this even more. If a window crashes in KDE you really open a terminal and start typing commands?! Or you will put icons on desktop?! Come on people... Shortcuts are meant to replace these long procedures. KDE's keyboard shortcuts can be easily configured through kcontrol. Opening a terminal in these situations can look very professional like, but it is nothing more than a useless thing to do in most situations. If you kill an app, and you can sense some performance loss, than there is the time to open consoles, ksysguards, etc. Usually, when applications freeze, they don't freeze other libs or apps, so "terminaling" is useless thing to do (Only in most situations, of course there can be some exceptions). Use shortcuts! Shortcuts are your friends!