I thought KDE is better than Gnome, and installed kubuntu-desktop on my Ubuntu 8.10 to get KDE.

But then I found out my computer can't run KDE without serious laag, and now I want Gnome back.


I tried switching back to Gnome, but now this is totally messed up. It's half Gnome and half KDE, plenty of bugs, and I got tons of KDE apps that I don't need.

So I just want to remove package "kubuntu-desktop" and all it's dependencies. Maybe there's a fast and easy way to do it?

I may/will want to do this for some other packages too.

Thanks.

Actually, you don't want to remove kubuntu-desktop's dependancies because it depends on a lot of packages that are necessary in your system in order to function. You want to remove kubuntu-desktop and all the dependancies that are not needed by other applications you use, but not all of them.
As far as I know, apt-get doesn't record which packages you installed explicitely and which packages were pulled by apt-get (unlike portage or urpmi), unless I am wrong (please tell me so).
I'm afraid you will have to investigate and remove the packages you don't use by hand.
apt-cache depends kubuntu-desktop is a good start...

"apt-cache depends kubuntu-desktop" gives a long list.

As you said, some of them are also needed by Gnome/Ubuntu as well,
so how can I know which packages I can safely remove?

you can use the apt-cache whatdepends packagename to know which package depends on packagename. You can safely remove the packages you don't use, but that apt-get can't know. Indeed, apt-get lacks this feature that records which packages were explicitely installed and which ones were pulled by apt-get, unless I'm mistaken. emerge and urpmi have that feature, but unfortunately not apt-get. It's sad but I'm afraid you have to take them one by one and remove those you know you don't need or those you know you don't want.