Open up an xterm. The following will give you a list of installed packages starting with 'k'
dpkg -l | grep ^ii | cut -f3 -d ' ' | grep ^k > pkglist
Then edit pkglist, removing the names of the packages you want to keep
, and then issue (as root) an "apt-get remove --purge $(cat pkglist)"; you may want to shut down X before doing so--not that I think you have
to, but I suspect that running new kde progams will be... difficult, what without the KDE libraries and all. Also, after removing the packages, you can delete pkglist.
For a more lightweight wm, I can recommend (well, I use) fluxbox. See also the member choice awards here on LQ. I don't know about java or tvtime, but I highly suspect that both are completely wm-agnostic. If you also want a light-weight (textual) browser, I can recommend elinks. (apt-get install fluxbox; apt-get install elinks).
Hope this helps --Jonas